ADC announced that West Central Telephone Association in Sebeka, Minnesota, will deploy ADC's OmniReach(TM) FTTX Solutions to support its all-fiber network infrastructure.

By converting entirely to fiber-optic cables and by putting every customer within 12,000 feet of one its 88 digital loop carriers, West Central Telephone is readying its 602-square-mile service area in rural Minnesota for high-tech jobs in the digital economy. West Central Telephone provides long-distance, Internet, and cable TV to its customers, in addition to local phone service. The rural telecommunications cooperative also provides interactive TV for area schools.

"Our investment in a fiber infrastructure, including ADC OmniReach FTTX solutions, allows us to offer our customers state-of-the-art technology," said Anthony Mayer, general manager for West Central Telephone. "As a result, we've recruited new businesses to this part of Minnesota that would otherwise not have been attracted to this rural area. Our investment in fiber is what allows us to offer cutting-edge communications technology and positions us for future economic growth."

West Central Telephone's FTTX deployment includes ADC OmniReach Fiber Distribution Terminals for centralization of splitters in the field. This outside plant cabinet is designed specifically for FTTX applications, with features that directly impact the reliability, functionality, and operational cost of the network, including 1X32 splitters with strain relief for the output pigtails and connectorization and splicing options of the input fiber.

As a global company with its world headquarters in Minnesota, ADC is proud to work with West Central Telephone and other rural cooperatives in promoting economic development for their communities with the installation of fiber infrastructures," said Pat O'Brien, president of the Global Connectivity Business Unit for ADC. "Minnesota's telecommunications companies and cooperatives with the foresight to install fiber in their communities do so as a way to stay viable in the new information-based economy. Our FTTX solutions are the perfect fit for rural telcos who want to make an investment in their futures and ensure that their networks can efficiently scale to support new telecommunication services vital to community development and long-term economic viability."

It is estimated that $1.5-3.5 billion will be spent annually by telecommunications service providers during the next five years as FTTX networks are deployed in the United States. New FTTX projects initiated by carriers and municipalities have increased by more than 100 percent since 2000.

Share prices of Copper Mountain [CMTN] tumbled Wednesday on news that the Palo Alto-based DSL solutions provider expects dramatically lower revenue and earnings in the fourth quarter of this year due to a slowdown in spending by competitive local exchange carriers.

On Wall Street, Copper Mountain melted down as its stock dropped $17 1/32, or 63.37 percent, to close at $9 27/32.

"[In] light of recent reductions in capital expenditure forecasts from many of our CLEC customers, we expect revenue and earnings to decline in the fourth quarter of 2000 on a sequential basis," Copper Mountain President and CEO Rick Gilbert in a statement following the company's third quarter financial report.

Net revenue for the third quarter rose 192 percent over the same period last year to $93.5 million, and profits for the third quarter beat Wall Street estimates.

However, the company's outlook for the fourth quarter and next year were apparently enough bad news to send its stock plummeting as investors focused on its dependence on the highly competitive CLEC sector.

"For the fourth quarter we currently expect to achieve net revenue of approximately $60.0 million and pro forma, fully-taxed, earnings per share of between $0.04 and $0.06. We expect these trends in the service provider landscape to impact our financial results for 2001 as well," said Copper Mountain in an earnings statement.

With most CLECs remaining in the red, many analysts expect buyouts and consolidations in the industry to accelerate in the future.

"There is no question that there will probably be consolidation," said Association of Communications Enterprises Executive Vice President David Gusky. "In the end, you will probably end up with a healthier industry."

AMP NETCONNECT XG UTP System consists of unshielded, twisted-pair cabling that supports 10G Base-T and enables 10 Gigabit Ethernet transmission over full 100 m channel. System has been tested to 625 MHz in worst-case scenario installations and has demonstrated Shannon Capacity of greater than 19 Gb/s.

The technologically advanced UTP solution for 10 Gigabit Ethernet Networks

HARRISBURG, Pa. - Jan. 24, 2005 -Tyco Electronics announces the AMP NETCONNECT XG UTP Copper Cabling System Solution for 10 Gigabit Ethernet applications. The unshielded twisted-pair system delivers the performance needed to support 10GBASE-T and enables 10 Gigabit Ethernet transmission over a full 100-meter channel, representing the application of several technological advances in cable and connectivity design.

"These advances don't come easily or inexpensively," noted Jim Crompton, global product manager, Tyco Electronics. "Fortunately, the combined global resources of Tyco Electronics were able to team together, build on a vast experience in materials, electronics and copper cabling systems, and then develop a global solution suitable for the IEEE 10 Gigabit Ethernet application to the full 100 meters."

"This product set represents a real technological break-through," says George Sharp, copper cable product manager, Tyco Electronics. "Existing UTP cables are adversely affected by crosstalk. Thanks to a coordinated effort inside Tyco Electronics, we were able to develop a solution that provided the necessary performance to overcome the crosstalk limitations through a combination of new materials, new manufacturing technology, and advanced test and measurement methods."

Brian Davis, copper connectivity product manager, Tyco Electronics adds, "The advances in cable technology dovetail with the advances in our copper connectivity, so a complete end-to-end Augmented Category 6 solution with cables, connectors, patch cords and patch panels could come to market simultaneously. The intrinsic interactions between cable and the connectivity required a mutual optimization development to ensure the complete, installed channel provides the necessary performance."

The XG UTP Copper Cabling System completes Tyco Electronics' entire AMP NETCONNECT XG Cabling System Solutions portfolio for 10 Gigabit Ethernet, which already includes single-mode fiber, multimode fiber to 300 meters (XG Fiber Cabling System), STP copper cabling to 100 meters (XG Copper Cabling System) and now UTP copper cabling to 100 meters (XG UTP Copper Cabling System).

"Today's network designs demand media that can support the full 100-meter distance for horizontal channels. Those looking for 10 Gigabit capacity over a copper system now have two choices that do just that," says Bob Zahr, RCDD/LAN specialist and systems engineering manager, Tyco Electronics.

Allan Nielsen, AMP NETCONNECT Products Standards Manager for Tyco Electronics in Europe, Middle East and Africa added, "We challenged the development team to come up with a global solution and they delivered. Our global company now offers a complete portfolio of global 10 Gigabit solutions."

The AMP NETCONNECT XG UTP Copper System has been tested to 625 MHz in worst-case scenario installations and has demonstrated a Shannon Capacity of greater than 19 Gb/s, nearly twice the capacity of existing Category 6 UTP.

For more information about all of Tyco Electronics' AMP NETCONNECT XG Cabling Systems, visit www.ampnetconnect.com/xgsystems or call customer service at 1-800-553-0938.

The AMP NETCONNECT business unit of Tyco Electronics develops, manufactures, and supplies a comprehensive range of communications infrastructure products and systems for customers in government, education, healthcare, finance, manufacturing and technology markets. Having established itself as the preeminent provider of commercial premises structured cabling systems for optical fiber and twisted-pair copper technologies, Tyco Electronics has broadened its AMP NETCONNECT product portfolio to include a complete line of residential cabling solutions. Coupling this spectrum of industry-standard offerings with its superior customer service, the AMP NETCONNECT business unit is well positioned as a single-source system provider to meet the disparate communications infrastructure needs of commercial and residential customers.

Tyco Electronics, a business segment of Tyco International Ltd., is the world's largest passive electronic components manufacturer; a world leader in cutting-edge wireless, active fiber optic and complete power systems technologies; and a provider of premise wiring components and systems. Tyco Electronics provides advanced technology products from over forty well-known and respected brands, including Agastat, Alcoswitch, AMP, AMP NETCONNECT, Buchanan, CII, CoEv, Critchley, Elcon, Elo TouchSystems, M/A-COM, Madison Cable, OEG, Potter & Brumfield, Raychem, Schrack, Simel and TDI Batteries.

copper premiums have weakened on softening demand as consumers work off inventories and continue to sit out of the spot market.

The premium spread has widened slightly to 5.25 to 6 cents a pound delivered from 5.5 to 6 cents previously.

"Consumers have been working off left-over inventory for the last two months so demand on the spot has slipped," one trader said. "Premiums have come down a bit. There's plenty of material coming into the Gulf port, and even consumers in the Northeast of the country are not knocking down the door."

With demand in the United States and China softening, some producers are building up stocks and this could knock premiums down further, another trader said. "Chile is not selling much to China so far this quarter. I think some of the producers have accumulated more stocks than they'd like to acknowledge. Producers are trying to ship material to fabricators earlier so that the surplus doesn't show up. Trying to sell material on the spot market isn't appealing because offers for tenders have been so low."

Copper premiums, which went as high as 8 cents a pound, have declined steadily since the end of November after strike action ended at troubled producer Asarco Inc., Tucson, Ariz., and Falconbridge Ltd.'s Kidd Creek complex in Timmins, Ontario.

Demand for material from consumers has declined as many copper-product manufacturers report a drop in business activity since the Christmas holiday shutdown.

The reporting of stocks at the newly Comex-registered Port of Panama City warehouse in Florida had little effect on the market, traders said. The warehouse had a total of 33,511 short tons of copper at the end of Wednesday, the latest data available, with 1,376 tons on warrant and 32,135 tons non-warranted.

But traders said the reporting of stocks was still causing confusion in the marketplace.

The New York Mercantile Exchange has come under fire for reporting the total amount of material at Panama City despite the fact that most of it is already sold to consumers. Nymex's nonferrous metals committee will review next week the reporting of stocks.

"We're still receiving a lot of calls on this and some people have taken this information as some hidden stocks that have been finally located," the second trader said. "We hope to get some resolution on this issue after the meeting next week."

Battery-actuated PATRIOT[R] PATCUT245CUAL-18V is capable of cutting cable up to 2.45 in. OD. Ergonomic design allows one hand operation, so user has one hand free to manipulate conductor into proper cutting position. Latch-style cutting head allows interference-free closure for mid-span cuts, and rotates 180[degrees] to allow users to get into tight areas. Tool comes with high-impact carrying case, tool retention lanyard, battery charger, and two 18 V Ni/MH batteries.


Advanced Design High-Speed Pump Completes Tough Cuts Faster

FCI-BURNDY[R], a leading manufacturer and provider of connector solutions to the industrial, energy, application tooling and automotive industries, introduces the PATRIOT[R] PATCUT245CUAL-18V battery actuated hydraulic cutter for the electrical market. Compact, fast, and easy to use, the PATCUT245 incorporates the latest in battery tool technology.

Intended for copper and aluminum cable only, the PATCUT245CUAL-18V is capable of cutting up to 2.45 inches (outside diameter) of cable and has a larger cutting capacity than another recently introduced battery actuated hydraulic cutter, the PATCUT129.

The ergonomic design allows one hand operation, so the user has one hand free to manipulate the conductor into the proper cutting position. Also, the PATCUT245 incorporates a specialized latch-style cutting head that allows interference-free closure for mid-span cuts, and it rotates 180 degrees to allow users to more easily get into tight areas.

The PATCUT245 comes equipped with a high impact formed carrying case to hold the tool, a tool retention lanyard, a battery charger and two batteries. The tool operates on industry-standard 18-volt Ni/MH batteries that eliminate voltage depression or "memory" issues. The PATCUT245 also features the addition of a reliable mechanical ram release that helps prevent depletion of battery power.

Measured by volume, scrap iron and steel remain the kings of the mountain for metals recyclers. But measured by profits, there are times when the nonferrous business is the segment that alert scrap recyclers pay close attention to when managing their operations.

While scrap dealers can rightfully consider 2003 and 2004 as terrific years to be in the scrap iron business, they would also have to acknowledge that the prices they received for their copper scrap were memorable, as well.

Increasingly, traditional ferrous scrap processors have abandoned any previous notions they may have had to treat the nonferrous side of the business as a secondary pursuit. Part of this reason could also be that a number of operational and bottom-line trends have helped to make it increasingly difficult for scrap companies to consider themselves stand-alone ferrous scrap processors.

CHANGING TIMES. Throughout the last several decades, several trends have worked to bring ferrous and nonferrous scrap operations closer together as two parallel parts of the same operating unit.

* In manufacturing, an increasing number of appliances and machines are made with a combination of ferrous and nonferrous metals fastened together in a variety of ways. In the automotive sector, aluminum producers jumped on the "lightweighting" bandwagon by selling the merits of aluminum as a less weighty substitute for steel or iron for a number of components.

* In processing, the shift toward shredding plants has seen traditional ferrous scrap processors take in appliances and auto bodies, regardless of the nonferrous content. In fact, the deployment of downstream shredder sorting systems has made the recovery of the nonferrous portion an important profit center for traditional scrap iron dealers.

* Also on the processing side, a drive toward efficiency and controlling labor costs has meant that scrap companies are increasingly unwilling to engage in manual sorting or disassembly to separate ferrous metals from nonferrous metals prior to size reduction.

* On the buy side, obsolete scrap has become an increasingly larger percentage of the overall scrap stream. In the United States, many scrap processors have seen their manufacturing clients close down, move offshore or become markedly more efficient (thereby reducing the amount of scrap generated). This has helped push the trend toward more shredding plants to make sure processors get in on the obsolete scrap stream, which continues to flow in every region of the country.

The popularity of the auto shredder is a common theme in these trends, and it--more than anything--has helped turn ferrous processors into dual ferrous and nonferrous firms.

The types of nonferrous scrap that a recycler can deal in are enough to fill a book (the fattest section of the Institute of Scrap Recycling Industries Inc.'s "Scrap Specifications Circular," as a matter of fact), and many of these metals show up in the post-shredder stream.

A look at the headquarters addresses of the companies on the 20 Largest Nonferrous Scrap Processors List shows a preponderance of Northeast and Great Lakes region addresses, with only two companies from the booming Southern states listed.

Dallas-based Commercial Metals Co. and New Orleans-based Southern Scrap Recycling may be the only two companies based in the South that made the list, but they by no means are the only companies with a presence in the South.

OmniSource Corp. has a plant in Decatur, Ala., as well as a string of facilities in the Southeast operating as part of its Carolina Recycling Group affiliate. Metal Management Inc. operates yards in Mississippi, Tennessee and Texas, while PSC Metals Inc. has several locations in Tennessee.

Much of the scrap handled by the David J. Joseph Co. runs through its River Metals Recycling facilities in Kentucky or its Trademark Metals Recycling facilities in Florida.

Additionally, Ferrous Processing & Trading (parent company of SLC Recycling) has a facility in Miami; Simsmetal America has established operations in Virginia, partly to supply the Chaparral Steel mini-mill in that state; and both of Global Recycling Inc.'s physical yards are in the Southeast (in Arkansas and North Carolina).

METHODOLOGY. For purposes of compiling this list, we asked recyclers to concentrate on the most commonly traded nonferrous metals--aluminum and copper. Certainly, there are other metals and alloys to consider, and some may provide a topic for a future list.

Whether to add in stainless steel processing was another question. This iron-bearing metal with a price pegged to its nonferrous alloying elements has a habit of raising classification questions. (See "Straddling the Stainless Fence," below.)

Ultimately, focusing on aluminum, copper and the nonferrous portions of the auto shredder stream provided a yardstick we hoped could be applied evenly.

As with all "20 Largest" lists that we compile, we received replies from some but not all of the companies we contacted. In some cases, we placed companies on the list based on estimates from industry sources, while in other cases we refrained from doing so.

Copper futures surged Thursday on the back of heavy fund buying, traders said.

"It's all fund related," one trader said, noting that buying seemed to be focused on the Comex division of the New York Mercantile Exchange. The July Comex copper contract hit an intra-day high of $1.282 a pound, up a little more than 5 cents from Wednesday's close at $1.2315, and ended the day at $1.273 a pound, a 4.15-cent gain.

The three-month copper contract on the London Metal Exchange made similar, though less lofty, strides. The metal gained $32 in Thursday's second ring to close at $2,727.50 a tonne vs. Wednesday's $2,695.50-a-tonne close, and notched another $47.50 gain in after-hours trading to close the final kerb session at $2,775 a tonne.

"There seems to be some misleading information out of China this morning, suggesting that there could be a shortage of copper in China as early as June due to the diverting of metal from Shanghai," another trader said. "That made people nervous. They started buying and that triggered short covering from the funds."

Reports of a shortage pending in China was misinformation, he said. "There are mountains of copper sitting in warehouses over there."

Another trader mentioned metal that was on its way to the United States from Chile. That influx of metal, plus a positive outcome from contract negotiations at Noranda Inc., Toronto, could have an immediate impact on premiums for physical metal.

"We're sitting on pins and needles to see if Noranda settles or not," the trader said of the ongoing contract negotiations between the company and the United Steelworkers union at Noranda's Canadian Copper & Recycling (CCR) refinery in Montreal East, Quebec (AMM, May 26). If there was a contract settlement, premiums could fall by as much as a cent a pound, he added.

This paper presents experimental evidence suggesting that electromigration (EM) can be a serious reliability threat when the dimension of Cu interconnects approaches the nanoscale range. To understand the failure mechanism prevailing in nanoscale Cu interconnects, single-level, 400-[mu]m long interconnects with various effective widths, ranging from 750 nm to 80 nm, were made, EM tested, and characterized in this investigation. The results indicate that interface EM (Cu/barrier) may be the predominant EM mechanism in all line widths. The evidence supporting the active Cu/barrier interface EM includes the fact that the EM lifetime is inversely proportional to the interface area fraction. Microscopic analysis of the failure sites also supports the conclusion of interface EM because voids and hillocks are found at the ends of the test strip, which is not possible if lines fail by grain-boundary EM in the test structure used in this study. In addition, our study finds evidence that failure is assisted by a secondary mechanism. The influence of this factor is particularly significant when the feature size is small, resulting in more uniform distribution of failure time in narrower lines. Although limited, evidence suggests that the secondary factor is probably attributed to pre-existing defects or grain boundaries.

Key words: Electromigration, Cu interconnects, interface, diffusion barrier

INTRODUCTION

Reliability of Cu interconnects is a critical concern for the microelectronics industry, particularly with aggressive development toward 90-nm and 65-nm technology where the feature size of Cu interconnects is also in the nanoscale range. Such ultra-fine Cu interconnects are expected to be more prone to physical failures, not only because they are subjected to more strenuous use conditions, but also because the critical size for fatal defects, either as processed or developed, is smaller.1 All these conditions are especially problematic to electromigration (EM) reliability and are expected to pose significant technical challenges. Although much research attention has been directed toward reliability of Cu interconnects in general, few studies on EM reliability of nanometer-range interconnects have been published.2 Study of this subject is particularly important because recent studies, including our own, suggest that interface EM is likely to be the most active EM failure mechanism in Cu.3-9 With the decrease in feature size, interface area fraction inevitably increases, particularly in the case when the thickness is kept constant. With an increase in interface area fraction, ultra-fine Cu interconnects may suffer increasing EM damage.

One of the most important factors to consider in conducting an EM mechanism study is the selection of the test structure. The EM studies are often conducted with two-level structures where either drift kinetics or the reliability of the via can be measured. As vias are generally the weakest link, this is a practical structure for evaluating overall interconnect reliability. On the other hand, failure is forced to occur in or adjacent to the vias, and determination of the mechanism, for example, whether it is grain boundary or interface, is not straightforward. In addition, the influence of other factors, such as pre-existing defects, may be hidden and difficult to isolate from the primary mechanism. EM testing can also be done on a single-level structure. In this case, the results have less practical value; however, as the failure in a single-level structure is more sensitive to microstructural details, it is advantageous in investigating the failure mechanism and other factors that influence the mechanism. A few points of investigative focus when using a single-level interconnect are failure statistics, activation energy, current density exponent, and failure morphology. Among these, failure statistics and failure morphology are particularly useful because they reflect the interaction between the primary EM mechanism and microstructural details.

Because understanding of the EM failure mechanism in ultra-fine, damascene Cu interconnects is the prime objective, this investigation used a single-level structure and examined parameters indicative of the failure mechanism prevailing in Cu interconnects. For this, five line widths, 750-80 nm, have been subjected to accelerated EM testing. The results lead to two main conclusions. The first is that EM through the Cu interface is the primary EM mechanism. This conclusion is deduced from the fact that lifetime, measured by median time to failure (MTF), shows a linear dependence on the reciprocal of the interface area fraction. It is further substantiated by the fact that void and hillock formation is limited to the two ends of the test strip. The second conclusion is that there exists a secondary mechanism that further accelerates the failure. The exact nature of this acceleration factor is currently unknown; however, there are several indications that it is probably related to structural defects. These observations are summarized in this paper along with a brief discussion of their physical significance.

Copper-oxide coating applied onto the copper substrate has emerged as an alternative to metallic coatings to improve adhesion with polymeric adhesives and molding compounds. The interfacial-bond strengths between the black oxide-coated Cu substrate and epoxy-based, glob-top resin were measured in button-shear tests, and the failure mechanisms were identified from the fracture-surface examination. The emphasis was to establish the correlation between the coating thickness, the surface roughness, and the interfacial adhesion with respect to treatment time. It was found that at the initial stage of treatment a thin layer of flat, cuprous oxide developed, above which fibrillar-cupric oxide was formed with further treatment until saturation with densified fibrils at about 150 sec. The interfacial-bond strength between the oxide-coated copper substrate and glob-top resin increased gradually with increasing treatment time, until the bond strength reached a plateau constant after a treatment for about 150 sec. There was a functional similarity between the oxide thickness, the surface roughness, and the interface-bond strength with respect to treatment time. A treatment time of 150 sec is considered an optimal condition that can impart the highest interface adhesion.

Key words: Interfacial adhesion, copper substrate, black oxide, coating thickness, surface roughness

INTRODUCTION

Delaminations at various interfaces are one of the most critical reliability issues in plastic packages,1 so significant research has been performed to improve the interface adhesion between copper-lead frame/substrate/foil and many different types of organic resins/adhesives/prepregs. Strong adhesion of metal to polymer has been achieved by modifying the chemistry and topography of the metal surface. Surface chemistry has been modified through plating with metals, such as Au, Ag, Ni, and Pd;2 applying a primer with an organic inhibitor, such as benzotriazole;3 vacuum deposition;4 ion implantation; and ultraviolet cleaning. Mechanical roughening has also been successfully employed to modify the topography of the metal surface.

In addition to the aforementioned metal plating, cleaning, and mechanical roughening techniques, copper oxide is another useful chemical-conversion coating for improved adhesion of copper with various polymers and has been widely employed since the early days of printed-circuit technology.5 The black-oxide-treatment process was originally developed to produce an antique black finish on copper and brass parts for decorative applications. To form the oxide coatings, sodium chlorite and sodium hydroxide are used at high concentrations and temperatures near boiling points. The black oxide treatment is commonly used to increase the bond strength between the copper and organic prepreg layers in multilayer printed-circuit boards (PCBs).6,7 The effects of coppe-roxide coating in PCB applications are known to be two-fold: one is to increase the available surface area for bonding by growing copper-oxide crystals; and the other is to passivate the copper surface to prevent contamination during manufacturing processes at elevated temperatures. The recent rapid growth in multilayer PCB production and the extension of copper-oxide coating technology to integrated circuit (IC) packages, especially for copper-lead frame and tape ball-grid array (TBGA) packages,8 have necessitated a more detailed optimization of coating materials and processes for improved adhesion characteristics and manufacturability in assembly. In a typical TBGA package, a glob-top resin encapsulates the die and wire-bonding assembly on a copper heat sink/stiffener, whose surface needs to be treated to achieve strong adhesion with the glob-top resin and tape adhesives.

Three different types of copper oxide with distinct colors, namely, black oxide, brown oxide, and white oxide, have been developed with different performance and applications because of their different crystal structures. The classic black oxide is most common and widely used, as it can be processed at low temperatures. The outer surface of the black oxide layer is primarily cupric oxide (CuO), and there is a gradient through the thickness that becomes progressively richer in cuprous oxide (Cu^sub 2^O).9,10 The long, acicular-cupric crystals pose significant problems of easy removal from the base copper when subjected to scrubbing and contact during subsequent assembly processes. To avoid unwanted removal of the loosely bonded oxide layer, several surface-hardening techniques have been applied based on a shot-peening process with tiny, hard particles, such as glass beads or alumina. To retain the bond strength in high-temperature PCB lamination processes, new oxide processes were developed, producing more densely packed, shorter needle crystals with brown color across the surface.11 White oxide is a primer system, consisting of multiple layers of tin/tin oxide and a cross-linking silane agent on the copper surface. Passing through a tin-sulphate spray chamber forms tin/tin oxide layers, while applying a solution of organosilane forms the cross-linking layer on top of the tin oxide layer. The tin-silane multilayers can have very strong covalent and polar bonds through double-bonding mechanisms between the silane and polymeric resins.12

In October 1995, two new 100-Mbit/s local area network standards were published by the Institute of Electrical and Electronics Engineers: IEEE 802.12, based on a demand priority (DP) access method, and IEEE 802.3u, based on a collision sense multiple access/collision detection (CSMA/CD) access method. Subsequently, there has been much interest in increasing the operating speed of these standards beyond 100 Mbits/s.[1] This imposes design challenges for the two media involved: optical fiber and copper cabling. Optical-fiber-based approaches are discussed elsewhere in this issue. Here we will examine schemes that are designed to use existing" copper cable installations, specifically data-grade cable, Category 5. This cable is already installed in locations that have foflowed building wiring standards.

A critical objective for the copper solution was to cost less than the fiber solution and this meant low complexity was required. We show that transmission at 424.8 Mbits/s using Category 5 cable can meet both industrial and the more stringent domestic emissions regulations. Furthermore, the design is robust in operation and of a complexity not greatly in excess of that used for the 100-Mbit/s rate.[2] The data rate of 424.8 Mbits/s is equivalent to the Fibre Channel rate of 531 Mbits/s before 8B10B coding (mapping 8 bits to 10 bits) and was chosen in anticipation of other IEEE 802 physical layers (PHYS) also fohowing the route of compatibility with Fibre Channel speeds to leverage existing components.

Compared with fiber, a copper system has a number of problems peculiar to it. A long metallic conductor is prone to act as a radio antenna, and this could lead to interference with other equipment (emissions) and unwanted pickup from other equipment (susceptibility). In addition, the copper cables are isolated by transformer coupling to avoid ground loops and other undesirable dc effects. These properties together with the transfer characteristic of the cable determine what can be successfully transmitted over the cable in a real-world environment.

Architectural Requirements: Speed, Bidirectionality

In a shared-medium access method such as DP or CSMA/ CD, full-duplex data transmission is not possible, since only one station (or none) has access to the shared channel at any point in time. However, half-duplex data transmission is suitable and an important refinement is possible. Network control traffic, including, for example, requests for access to the shared media, can be allowed to travel upstream when data flow is downstream, or vice versa. This helps the efficiency of the network, making it into a hybrid duplex scheme in which data and control can flow simultaneously in opposite directions, but neither is full-duplex.[3]

Having four pairs in one Category 5 cable means that there are alternative duplexing schemes to the traditional singlechannel frequency-division multiplexing (FDM) or hybridplus-echo-canceller approach. The bandwidth of one pair can be dedicated to a reverse control-signaling channel with the remaining three pairs for the forward data channel. This 3 + 1 scheme creates an asymmetric duplex scheme in terms of the bandwidth available in each direction. Having the still relatively high bandwidth of a single pair for control signaling is useful not because control traffic is high-bandwidth but because prompt detection of control codes is advantageous in terms of network performance. Asymmetric duplexing using selected pairs is notably less complex than FDM or hybrid plus echo canceller because of the lower component count. As shown in Figure 1, only two of the four pairs need be half-duplex; the other two can be simplex. Near-end crosstalk (NEXT) is no longer the dominant noise source in this Category 5 system as it was in the Category 3 100-Mbit/s systems.[5] Extenally induced noise is doniinant. Having a solution without FDM, echo cancellation, or NEXT cancellation is the pivotal step in forming a low-complexity system design.

Speeds greater than 100 Mbits/s are of interest for extending the existing standards, and in particular, speeds matching the Fibre Channel rates offer the possibility of leveraging existing components including drivers and clock recovery circuits. The first two Fibre Channel rates offering a marked speed increase over 100 Mbits/s are 531 Mbits/s and 1062.5 Mbits/s. However, these include the overhead of an 8B10B code designed assuming a single serial transmission medium. Since the copper solution divides the data among three pairs, the 8B10B code could be replaced with something more appropriate for this application. The raw data rates for the two Fibre Channel rates then become 424.8 Mbits/s and 849.6 Mbits/s. Extending these rates to the 3 + 1 asymmetric duplex scheme gives per-pair rates of 141.6 Mbits/s and 283.3 Mbits/s.

Signaling: Multilevel Signaling, Coding, Control

Earlier work[6] had shown that transmitting basic NRZ data at 155 Mbits/s was unlikely to satisfy domestic emissions regulations (e.g., FCC B) and might even prove problematical in meeting the less stringent industrial regulations (e.g., FCC A). Regulations begin at 30 Mhz, so reducing transmitter spectral energy above this frequency is an obvious approach to reducing emissions. Thus, a per-pair rate of 283.3 Mbits/s immediately seems far less suitable for a copper implementation than 141.6 Mbits/s. Several bandwidth compressing modulation schemes were studied, including quadrature amplitude modumon (QAM), partial response (PR) changes I and IV, and pulse amplitude modulation (PAM).[7,8] QAM is a two-dimensional scheme requiring complex in-phase and quadrature filters, and while PR has good bandwidth compression, this comes at the expense of clock recovery. PAM requires dc balancing but is a relatively straightforward scheme to implement and when m levels are used reduces bandwidth requirements by 1092(m). If excess bandwidth a is also reduced below 100% then an extra factor (1 + [alpha])/2 is gained to give the overall relationship:

Copper and its alloys provide excellent electrical and thermal conductivities, outstanding resistance to corrosion, ease of fabrication, and good strength and fatigue resistance. They are generally nonmagnetic, and can be readily soldered and brazed. Many copper alloys can be welded by various gas, arc, and resistance methods. They can be plated, coated with organic substances, or chemically colored to further extend the variety of available finishes.

Pure copper functions well in cables and wires, electrical contacts, and a wide variety of other parts that are required to carry electrical current. Copper and certain brasses, bronzes, and cupronickels are widely used ...

In her ongoing 2004 installation What Remains, Ruth Stanford, then a graduate student at Carnegie Mellon University, replaced the shattered windows of a long-abandoned row house adjacent to the Mattress Factory's main building with outward-facing carved granite panels visible only from a narrow alley behind the house. Part memorial and part local history project, and clearly resembling grave markers, the panels are inscribed with the names, ages and occupations (including, not coincidentally, a stone-cutter's) of the working-class immigrants who inhabited the house over the last century.

For the second part of the project, In the Dwelling-House (2006), Stanford moved indoors and mined the derelict house for all traces of human life--and when that was hard to come by, she culled bits of information from scraps of decades-old newspaper and frayed wallpaper. Artifacts excavated from the mostly darkened house, including cigarette butts, crayons, a sponge and copper muffin tins, are collected in glass jars and displayed in a spot-lit cabinet of curiosities in the front room. The various components of Stanford's other interventions require careful sleuthing by the visitor, aided by a flashlight.

The wallpaper in a ground-floor room that was once the kitchen is printed with a faded, barely noticeable geometric pattern that Stanford translates into red, yellow and black minimalist sculptures on waist-high marble pedestals. Were it not for the crumbling walls, peeling paint and bad light, this room could easily pass for a contemporary art gallery (the polished hardwood floor doesn't hurt). Elsewhere, a china cabinet is filled with nearly a dozen pink plastic lobsters, echoing a wallpaper pattern on the other side of the doorway. In a second-floor parlor furnished with a sagging sofa, an old black-and-white Zenith television plays looped footage from an Ali-Frazier fight. A scavenger hunt of nearby walls turns up a 1970s newspaper clipping about another boxing match, tacked next to a stamp-size reproduction of a poster for Jaws. The Jaws reference is extended in a slope-ceilinged room on the top floor, where Stanford has decorated one wall with a giant pencil drawing of a toothy shark. A cookout theme takes over another upper-floor sitting room, where a scrap of faded wallpaper comes to life in sculptural re-creations of a white picket fence, an overflowing bag of charcoal, a barbeque pit and a pig roasting on a spit.

Wandering around the creaking and dank house, one discovers pairs of watchful googly eyes and delicately drawn frames surrounding dusty raccoon tracks on the walls. Pittsburgh's North Side, where the Mattress Factory is located, is making a comeback from post-industrial abandonment and neglect. As a reminder of our collective past, Stanford's project subtly illuminates the life cycle of what was once someone's home.

EYE CANDY

Pass on run-of-the-mill basic browns and opt for rich updates instead. Tops on our list are warm, sheer toffee tones (left), as well as those tinged with a bit of metallic, like a rich topaz. We also like the new crop of iridescents that mix brown with vivid color and a touch of pearl. On the smoky side, colors are cool and woodsy (far left). When paired with such sultry accents as a copper or matte navy liner, these palettes become even edgier.

SWEET CHEEKS

Summer's hint of color on the apples of the cheeks has been given the brush-off; in its place comes a soft sweep of color placed high on the cheekbone. Warm cheeks anchor the face of fall, giving it a subtle definition that pulls the entire look together.

LUSCIOUS LIPS

A broad range of colors--from honeyed pales to deep espresso--dominated the runways. And the news on everyone's tips B that matte and soft satin finishes have upstaged last season's wet look.

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cheeks

The softly sculpted cheek, in browned hues, is one of the most graceful statements of the season

THE NEWS

Cheek color is essential to fall's nude-and-improved color palette. It breaks up the monotony of earth tones, adding dimension to the face. Here's how to play it up:

* Color: Look to sun-baked neutrals from butterscotch to brick, or brown-based hues such as muted roses or tawny oranges.

* Texture: The one you choose should be determined by your desired finish. For a luminous veil of color, gel sticks are best. For a soft wash, look to creams, and for a glamorous touch, powders can't be beat.

* Technique: Place cheek color high on the bone and extend it to the hairline. With cheek powder, use a large blush brush to sweep on color, starting at the beginning of the cheekbone and continuing upward. For creams and gels, apply product with a large wedge sponge, and blend, blend, blend!

"Most of us don't turn red or flush at the cheeks, which is why cheek color with browned undertones is so much more complementary on brown skin than traditional reds or pinks. They make our skin glow in a very natural way."

--Sam Fine. celebrity makeup artist samfine.com

Rich Picks

1. Tarte Cheek Stain in Sunkissed, $26, tartecosmetics.com.

2. Laura Mercier Lady Luxe Creme Cheek Colour in Riviera, $22, (888) MERCIER.

3. Pretty Pretty Face & Body Bronzing Powder in Filomena, $26, pretty2.com.

4. Trish McEvoy Blush in Perfect, $19, (800) 431-4306.

5. Make Up For Ever Powder Blush in #48, $15. (877) 757-5175.

6. Stila Color Push-Ups in Nude Flash, $20. (877) 565-1299.

7. Stila Color Push-Ups in Bronze Flash. $20, (877) 565-1299.

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eyes

Light and sheer, deep and well-defined--fall's new looks are worth warming up to

THE NEWS

It's a season dominated by surprising mixes of extreme shine and rich velvets. Textures also vary, with satiny eyeliners bordering whisper-weight eye shadows. The way to work it:

* Color: Earthy neutrals, from camel to raisin, suit just about everybody. High-voltage iridescents are also hot. Turn to olive, burgundy or bronze for a hit of wearable color. And the smoky smoldering eye has been reworked in woody tones as light as taupe, as deep as mink.

* Texture: It's all in the mix. Pick a cream, powder or gloss. Look to liners, both liquid and pencil, to add an ultrafeminine touch. In all cases it's time to embrace thickening mascaras--lush dark lashes are a must.

* Technique: Choose your eye style. (1) Play it straight with a single wash of color from lid to crease. (2) Take it to the next level and line, define and highlight with a combo of shades and/or textures. Line the top lid only, define the crease with a deep rich hue and highlight beneath the outer end of the brow bone. (3) Go for high drama by sweeping shadow from lid to brow, continuing the color beneath your lower lashes. Complete the look by rimming your lid with liquid liner or rimming top and bottom lids with a pencil.

"This season try using a brown eyeliner or shadow wherever you might have traditionally used black or gray. it'd less harsh and easy to work with or without accents of colors."

Recent progress on the thermodynamic databases of calculated phase diagrams in microsolders and Cu-based alloys is presented. A thermodynamic tool, Alloy Database for Microsolders (ADAMIS), is based on comprehensive experimental and thermodynamic data accumulated with the calculation of phase diagrams (CALPHAD) method and contains eight elements, namely, Ag, Bi, Cu, In, Sb, Sn, Zn, and Pb. It can handle all combinations of these elements and all composition ranges. The elements of Al and Au have also been added to ADAMIS within a limited range of compositions. Furthermore, a database of Cu-based alloys, including binary (Cu-X), ternary (Cu-Fe-X, Cu-Ni-X, and Cu-Cr-X), and multicomponent (Cu-Ni-Cr-Sn-Zn-Fe-Si) systems, has also been developed. Typical examples of the calculation and application of these databases are presented. These databases are expected to be a powerful tool for the development of Pb-free solders and Cu substrate materials as well as for promoting the understanding of the interfacial phenomena between them in electronic packaging technology.

Key words: Pb-free solders, thermodynamic database, Cu-based alloys, calculation of phase diagram, phase-field method, interfacial reaction

INTRODUCTION

During the past decade, Pb-free solders, to replace conventional Pb-Sn alloys, have been designed and developed to meet the requirements arising from environmental and health issues concerning the toxicity of Pb.1-3 Many investigations have indicated that Pb-free solders are likely to be multicomponent alloys because the melting temperatures of binary candidates are either too high or too low, and their mechanical properties are not adequate. In view of the necessity to develop Pb-free solders with high efficiency, and the transition time involved in replacing Pb-bearing alloys, a thermodynamic database of microsoldering alloys for reliable predictions of liquidus, solidus, phase fractions and constitutions, equilibrium and nonequilibrium solidification behavior, etc., in a multicomponent system is required because it is difficult to understand these factors from available references. In addition, a thermodynamic database of the Cu-based alloys is also important for the design of substrate materials. The calculation of phase diagrams (CALPHAD) is an effective method for alloy design4 and has been widely used in development of new materials.5 Recently, the present authors have developed thermodynamic databases for microsoldering materials6-8 and Cu-based alloys9 within the framework of the CALPHAD method. This database is useful for the design of Pb-free solders and Cu-based substrate materials as well as for understanding the interfacial reaction between them. In the present paper, the validity of these two thermodynamic databases for calculation, alloy design, and applications is demonstrated.

THERMODYNAMIC DATABASE OF MICROSOLDERS

A thermodynamic tool of microsoldering materials named Alloy Database for Microsolders (ADAMIS) was developed by combining the thermodynamic database of microsolders6-8 with Pandat, (Madison, WI) a multicomponent, phase diagram-calculation software program.10 In this database, the phase equilibria in any system that includes the elements Ag, Bi, In, Cu, Sn, Sb, Zn, and Pb can be calculated in the whole composition range. Recently, two elements, namely, Al and Au, were added to this database, and calculations are available for a limited composition range of these elements.

In the database, the thermodynamic parameters for describing the Gibbs energy of each phase are evaluated by optimizing the experimental data pertaining to the phase boundary compositions and thermodynamic properties, such as activity, heat of mixing, and enthalpy of formation. Regarding the present database, there are some important alloy systems for which there has been little or no experimental data. Thus, experimental work to determine phase equilibria, such as liquidus, solidus, isothermal and vertical sections, etc., has been carried out, and a better estimation of the thermodynamic parameters with good agreement between the calculated and the observed phase equilibria has been obtained.11-21 The thermodynamic parameters were optimized and evaluated by Thermo-Calc (Stockholm, Sweden) software.4

ADAMIS is a user-friendly thermodynamic tool for the design of microsoldering materials. Beginners can easily manage it through the Windows interface. The calculated results are independent of the user's level of expertise because it has the ability to automatically find starting points and initial values for stable phase equilibria.

Figure 1 shows the main contents of ADAMIS, where much information, such as phase equilibria, projection of the liquidus surface, and simulation of solidification etc., can be obtained. In addition, the surface tension and viscosity in the liquid phase can also be calculated.

THERMODYNAMIC DATABASE OF Cu-BASED ALLOYS

A thermodynamic database of Cu-based alloys containing Cu-X binary, Cu-Fe-X, Cu-Cr-X, and CuNi-X ternary and multicomponent systems was also developed on the basis of the CALPHAD method. An outline of the assessed systems is shown in Table I. To obtain a good assessment for thermodynamic parameters, experimental investigations of phase equilibria, including not only first-order phase transformation but also order-disorder transition for some important systems with no or very little experimental data, were carried out on the basis of differential scanning calorimetry, energy dispersive x-ray spectroscopy, the diffusion couple method, etc.22-29 For example, the ordering of the bcc phase has been determined in the Cu-Al,26 Cu-Sn,27 and Cu-Fe-Al systems.28