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Articles from 2006 In May

Comments on lead-free solders

Comments on lead-free solders

We found some very good comments on the question of lead-free solders and finishes from Joe Fjelstad on the Listserv LEADFREE page. Fjelstad makes a great case against going lead-free.

Fjelstad’s comments:

The point of concern and the lead-free movement was predicated in concernof the poisoning of children, especially the very young, in early,formative years, where the effects are most pronounced. Nearly all casespoisoning of children have been due to the ingestion of lead acetate used inpaint. Acetic acid (aka vinegar) will dissolve lead to form lead acetate(aka lead sugar) It was used in paint and paint chips are sweet. Lead acetatewas even used to sweeten wine in centuries past. Also there is tetra ethyl leadwhich was (and still is in some places) used as an antiknock ingasoline (petrol, benzene) This can be inhaled from fumes of combustion andan accumulation of lead in the body. Neither of these have the remotestrelationship to electronics save that the element lead was used in the creationof the organic products.

Elemental lead does not require the employment of a precautionaryprinciple. It simply requires due caution. Man made compounds, especially those without known analogues do require precautions.

In sum lead-free solder will not make the environment better, butit could well make it worse. It will not use less energy, it will usemore. It will not be cheaper, it will be more expensive. It will not makeelectronics more reliable, evidence is that it will make them less so.However, the crowning point is that the provisions of WEEE which requirerecycling, makes the matter of lead from a risk point totally moot while thenegatives and risks associated with going lead-free, in terms ofelectronic solders, will remain.

Mitigation techniques for tin whiskers, part two

Mitigation techniques for tin whiskers, part two

The first part of this article looked at the problems facing those industries that are exempt from RoHS laws. Defense, aerospace, medical equipment and parts of the telecommunications industry are not required to convert to lead-free components. However, these industries are still facing the prospect of using lead-free parts, since many of the leaded parts they have used in the past are being discontinued. Component manufacturers that have switched to lead-free versions will not long run two lines, one a high volume lead-free version for consumer products, and a second leaded version for the smaller exempt market.

This means the exempt industries will probably have to switch to lead-free parts, like it or not. The exempt industries suspected they would face this prospect and turned to industry groups to help develop policies for adopting lead-free parts while also trying to avoid tin whiskers. The International Electronics Manufacturing Initiative (iNEMI), put together teams to develop a list of recommendations for tin whisker testing and mitigation. The iNEMI teams took their research to the standard bodies JEDEC and IPC to create industry standard approaches to lowering the risk of tin whiskers.

The resulting standards include JEDEC's JESD201, "Environmental Acceptance Requirements for Tin Whisker Susceptibility of Tin and Tin Alloy Surface Finishes," and the JEDEC and IPC joint document, JP002, "Current Tin Whiskers Theory and Mitigation Practices Guideline." Joe Smetana, an Alcatel engineer and chair of iNEMI's Tin Whisker User's Group, notes that the documents don't eliminate the risk of tin whiskers even as they reduce the risk. "Although it is not possible to guarantee that whiskers will not grow under field conditions, the mitigation practices detailed in JP002, combined with the test and acceptance criteria outlined in JESD201, form a cornerstone of a three-fold strategy of mitigation practices, process controls and verification testing that helps to reduce the risks of tin whiskers."

A design engineer from Lockheed Martin who spoke to us on the condition of anonymity believes its time we learned more about what actually causes tin whiskers. At this point, whisker growth is still a mystery. There are mitigation strategies that reduce the risk - as in adding lead to pure tin solders and finishes - but we still don't really understand the physics of whisker development. "Nobody is willing to fund a detailed study on tin whisker growth and the physics of the whisker formation," says the Lockheed Martin engineer. "What is the acceptable overcoats, and what is the minimum overcoat thickness? What is the necessary stress to make a whisker grow? We don't know the answers."

The engineer believes the government entity best suited to funding and carrying out a study is the Department of Defense (DoD). "The DoD took the cheap way out and just said don't use pure tin," says the engineer. "But in the long run, it might be cheaper if the DoD and the electronics industry paid to solve the questions of whisker development."

Pre-RoHS business booming

Pre-RoHS business booming

A recent article in Design News sister publication, the UK-based Electronics Weekly, reports that business among contract manufacturers has increased in the past six months as companies prepare to deliver RoHS-compliant product into Europe before the July 1 RoHS deadline. Editor Richard Wilson quotes a number of marketing executives who are seeing a rush to get compliant product on the shelf before July.

The pre-RoHS mini-boom seems to be across the board, with increases in business noted by those in test equipment, printed circuit boards, component suppliers and contract manufacturers.

On the United States side of the electronics market, the rush to RoHS is not as pronounced. Distributors in North America have noted they are surprised by the lack of high demand for compliant components. Distribution executives say there is still considerable demand for non-compliant parts.

SMTA presenting talks on lead-free reliability

SMTA presenting talks on lead-free reliability

The industries exempt from RoHS – aerospace, defense and medical equipment – continue to struggle with their need mitigate tin whisker formation in lead-free components. As more and more component manufacturers discontinue their leaded versions, the exempt industries are looking for ways to switch to lead-free parts without risking tin whiskers growth and product failure.

This year, the Surface Mount Technology Association will present a series of workshops on the topic of using lead-free products under high-stress conductions at its annual conference held September 26 – 28 in Rosemont, Ill. in conjunction with the Assembly Tech Expo.

Courses will include Lead-free Reliability, Lead-free for Harsh Environments, Lead-free Manufacturing/Troubleshooting, Lead-free vs. SnPb, Reality of Reliability of Lead-free, and other courses of a similar nature. The titles reveal an obvious theme – exempt industries now recognize they will have to adopt lead-free parts and learn how to use these parts in such a way that tin whisker development and be managed.

REDEL® Plastic Connectors

Secure, durable connectors for medical equipment

LEMO's plastic connectors are geared toward the medical field. They use the Quick-Lok push-pull, self-latching system to attach securely. Their gold-plated-over-copper and-nickel connector contacts can take more than 1,000 mating cycles, and special plastics hold up well against repeated autoclaving. There are multiple key-way configurations and color-coding available, as well as reusable and disposable versions. LEMO offers more than 55,000 electrical, electronic, fiber optic and fluid connectors.


ZIGBEE INSIDE: Five New ZigBee-Based Wireless Systems

It has been a little over one year since the ratification of the ZigBee specification (December 2004), and the subsequent announcement on April 1, 2005 of four ZigBee-compliant platforms from Chipcon, CompXs, Ember and Freescale Semiconductor. Based on the recent and planned introductions of several ZigBee-based end products, the standard is starting to gain traction. The ZigBee Alliance has more than 200 Alliance Members and a presence in 24 countries on six continents. With OEMs and end-product manufacturers representing 30 percent of the global membership, ZigBee promises to enable new features in several leadership products.

This means homeowners will be able to buy off-the-shelf products that work together in a networked environment. In addition, heating, lighting and security systems in homes equipped with ZigBee-based networks can be easily reconfigured. In building automation, wireless monitoring networks with centralized management of lighting, heating, cooling and security systems will provide the flexibility to reconfigure systems to adjust for occupancy changes within a building.

What's a ZigBee?

Developed for low-rate personal area networking, ZigBee is a standards-based technology designed to address the unique needs of low-cost, low-power, wireless sensor networks for remote monitoring, home control and building automation network applications. The technology allows digital transmissions of up to 1 Mbps in the 868 through 928-MHz band or 2.4 GHz. To keep the power requirements low, the expected range is from 10 to 70 m. Using the IEEE 802.15.4 standard as a foundation, ZigBee's mesh network topology transmits a signal through redundant pathways providing improved reliability for wireless sensing and control.

The key to ZigBee's future growth is interoperability. Manufacturers, OEMs and developers can qualify products for one of three levels:

  1. ZigBee Compliant Platform modules or platforms that are intended to be used as building blocks for end-products.

  2. ZigBee Certified end-products built on a ZigBee Compliant Platform using a ZigBee public application profile.

  3. ZigBee Network Capable products built upon a ZigBee-compliant platform, but using a non-public ZigBee application profile.

  1. The reasons for selecting ZigBee over other wireless options are the same in most cases. Maura Turolla and Elisa Alessio of Telecom Italia summarized the reasons quite nicely in their presentation at the recent ZigBee Open House in Milan, Italy. Compared to other proximity radio technologies, such as RFID, Near Field Communication (NFC), and contactless, as well as Bluetooth, the main key-values driving the ZigBee choice are:

    • Pervasive Ad-hoc Self-organizing Mesh Networks (not limited to star topologies)

    • Configurable Radio Range

    • High Security Level

    • Easy integration in appliance/terminals in miniaturized peripherals with integrated antenna

    About the only ZigBee differentiators missing from their list were low cost per node and low power for longer battery life. Some applications may take advantage of just a few of these.
    ZigBee MomentumThere have been a few surprises in the end product activity over the past year. One is in the area of automatic meter reading — an initial target application for ZigBee. "The surprise is that (automatic meter reading) seems to be moving faster than I anticipated," says Bob Heile, chairman ZigBee Alliance. "Both the carriers and the utilities are seeing the future benefits of having a meter reading technology that can ultimately become a control technology." Automatic meter reading, combined with building control functions, allow load-shedding with minimal disruption and avoid performance penalties for brown-outs and black-outs. In addition, the combination allows handling peak power for a limited number of hours each year without adding new capacity that would be largely underutilized all the rest of the time.
    This provides a rather straight-forward and compelling solution to a very complex problem. For example, in commercial buildings with extensive deployment of ZigBee-based lighting controls, the lighting can be dimmed by 5 percent to handle a peak power situation based on the automatic meter reading input and the system's capability to control ZigBee-certified lighting. The 5 percent dimming would hardly be noticeable to building occupants. Heile says these systems are in the design and evaluation phase in the U.S. and other regions.
    The following five products and/or systems show the real power of the low-power ZigBee network. They are either currently or eminently available.
    1 Home Theater ControllerAVM-HTC1-B
    Control4 began shipping ZigBee Network Capable products in April. In addition to the theatre control of home audio and video equipment, the system includes wireless control capability to automate and remotely control several functions in the home. The wireless products can be easily retrofitted into the home to provide reliable, cost-effective control. Control4's systems approach includes wireless lighting, control systems, wireless dimmer, wireless outlet switch, remote HVAC controls, and servers for video and audio with control pads located around the house. ZigBee remote controls with displays interact with the system and ZigBee controls the entire infrastructure. The system uses optical fiber CAT5 and 802.11 for distributing wideband content. At the same time, the home theatre sets a predetermined lighting mode. The same system handles security from a central (or remote) control. The system's communications include:

    • Wireless ZigBee (802.15.4) mesh networking

    • Ethernet (802.3) 10/100base-T, RJ45 jack

    • WiFi (option) 802.11

    The system has multiple interfaces including Touch Screens, Keypads or the System Remote Control.
    Control of products located throughout the home occurs by IP-based communication over wireless 802.15.4 mesh networking or Ethernet. Specific ZigBee control products include the Wireless Outlet Dimmer that controls plug-in devices rated up 500 watts and the Wireless Outlet Switch that controls plug-in devices rated up to 15 amps.
    2 Home AutomationHome Heartbeat
    The Home Heartbeat uses a variety of sensors to monitor several functions and keep track of the home environment. The ZigBee-ready system consists of three basic components: sensors, a base station and a Home Key device. The base station receives the input from the sensors and determines the appropriate action. The Home Key device provides a removable display for the base station and a portable sensor monitor to display every function in the system. In addition, the key is the interface used to set up the system. A Water Sensor detects the presence or absence of water making it ideal to identify flooding. If water is detected, the Water Shut-Off Valve can turn off the main water supply line. Reminder/Timer Sensors provide a reminder to check items around the house or to perform a specific task on a regular basis, such as changing an air filter. Open/Closed Sensors identify an open window or garage door. The Power Sensor sends an alert if an appliance or electric device has been inadvertently left on. The Attention Sensor provides an immediate contact, like an instant messenger for the Home Key device. Planned additions to the system's capabilities include motion, gas detection and temperature sensors. The ZigBee protocol allows the easy addition and reconfiguring of these sensors.
    3 Wireless Home AutomationHomeRemote
    Hawking Technology
    With planned availability in July 2006, the HomeRemote System addresses new or existing home networks with ZigBee-ready wireless control. For homes without an existing home network, the Wireless Home Automation Gateway, which includes a Wireless-G router, provides wireless access for HomeRemote devices and sensors and WiFi Internet access for other networked computers. The gateway shares one broadband Internet connection among all the computers. For homes with an existing network, the Wireless Home Automation Hub provides wireless communication with HomeRemote devices. System components include:

    • Wireless Door/Window Sensor that detects the opening and closing of windows, doors, cabinets, pet doors

    • Wireless Power Outlet, a controlled power outlet for lights, televisions, computers, heaters or fans

    • Wireless 7-Outlet Power Strip has seven outlets for controlled power

    • Wireless Signal Extender that extends the wireless coverage area for the system for larger homes or remote, onsite buildings

    With the future availability of items such as Wireless Cameras, Audio Monitors, Sirens and Strobe lights, Motion Detectors, and Local Control Panels, the HomeRemote will tie a number of ZigBee nodes together.
    4 PDA CF CardCF card
    Telegesis is shipping initial quantities of its ETRX1CF, a ZigBee Network Capable Compact Flash (CF) type II card for PDA or portable computer applications. The unit enables a portable handheld product to communicate with other ZigBee modules. The node can be used in a PDA with a CF slot or in a laptop computer with a PCMCIA/CF adaptor. Telegesis provides drivers and support for Pocket PC and a simple terminal application program as a starting point for developers. Telegesis-developed software allows the CF card installed in a PC to function as a ZigBee development board using AT-style commands. Example commands include AT+SN (search ZigBee network and discover devices), AT+MCAST (sends a multicast), AT+BCAST:

    (sends a broadcast), and AT+ASS: (associate node). Similar to many WiFi PCMCIA cards, the antenna resides in the extension of the card, which is external to the PC or PDA.

    5 Gas Detection SystemWireless Gas Monitor
    Designed for parking structures, this industrial system identifies hazards and triggers the appropriate reactive measures such as ventilation activation. The VA301W wireless gas monitor uses electrochemical sensors to detect carbon monoxide (CO) and nitrogen dioxide (NO2) and operates for two years without calibration, maintenance, or battery replacement. The sensor's data is transmitted to the VA301C-W controller over a ZigBee-ready network with a secure 128-bit encryption. The VA301C continuously monitors up to 96 inputs/outputs, on three distinct channels, at distances of up to 2000 feet. The controller's zoning capabilities permit the averaging and comparison of multiple sensor readings. For the output control, the VA301R transmitters/relay module provides up to eight relays of 5A, 30 V dc or 250 V ac (resistive load) to activate fans, louvers, and other devices at programmable alarm levels. The unit's Modbus output can be converted to a BACnet output. The ZigBee wireless sensors allow the installation at a substantially reduced. In addition to avoiding the wires, the mesh network provides auto configuration. The low-power protocol also means reduced operating expense since the batteries can last for two years without replacement.

    //Check out the links below for more info//
    Panasonic Industrial Solution ZigBee Comm Module 802.15.4
    Wellspring Wireless Aqura Submeter
    Integration/CompXs USB ZigBee Dongle
    "Move Over, Bluetooth, ZigBee is Here," 03.15.04
    "Demo Kit Simplifies ZigBee Applications," 05.16.05
    "ZigBee Shrinks to One Chip," 07.18.05
    For info about the ZigBee Alliance:
    ZigBee Alliance Open House Presentations: 03.16.06

IK-TF2 3CCD Color Video Camera

Small, lightweight, easy to use

Made to fit into high-speed machine vision systems, the three-chip camera measures 44 x 44 x 78mm, and weighs just 5.47 oz. It has an RGB micro prism system, 570 TV resolution, and a 1/3-inch IT-CCD sensor (410,000 pixels). Easy integration is possible with a C-mount lens flange, on-screen menu, RS-232 serial interface, and a 2:1 interlaced scanning system. It is made for color web inspection, food sorting, packaging, color printing and other high-speed color imaging tasks.

Toshiba America

Point on a Wire

Consisting of an encoder or potentiometer and a wire that pays off a drum, a cable extension transducer provides inexpensive measuring over long distances because its wire needs no guidance to follow a straight line-only an attachment at the working end. Also called draw wire sensors, string pots, even yo-yo sensors, the devices can be installed without much fussing over alignments. They are built to withstand extreme environments, such as paper mills, or can be furnished as instrument grade styles that are at home in a lab.

Read the articles:
Space Age Control
Sick Stegmann

Useful Links
Information on other string pot makers and applications can be found at these websites.

IES5501 Bus Buffer circuit

New line allows daisy-chain configuration

The first in the IES550x family, the IES5501 Bus Buffer Integrated Circuit is made to simplify the design process, using analogue IC design principles for a digital bus. It is used in two-wire bus systems in telecommunications systems, CompactPCI, VME bus systems, RAID products, power management systems, backplane management systems, bus switch/multiplexing buffering and for bus voltage level translation. The buffer doesn't use rise time accelerators, using monolithic bipolar integrated circuit techniques. With low input to output offset voltages, it can be "daisy chained" and/or star configured. The buffer's bus voltages can be level shifted in a range of 1.8 to 15V. The enable pin supports input to output connection control. It comes in 8-pin SO, 8-pin MSOP and 8-pin DIP packages, the latter for sampling only.

Integrated Electronic Solutions

1070 Series AC True RMS

Accurate and durable transducers

This new series of RMS current transducers offer accuracy over a 20Hz-2KHz range. Available in 14 current ranges from 2A to 250A, they have an accuracy of 0.25 percent over a temperature range of -40 to 85C (-40 to 185F). They also have a wide voltage power range from 12V to 32V, and a current signal from 4mAdc to 20mAdc. They protect against reverse polarity and overload currents of up to 500A, plus a load resistance range from 0 to 300. They have an epoxy coating on the internal circuitry for insulation and protection from moisture and contaminants. They come built into a molded plastic, 94V-O flammability-rated case. Storage temperature is -55 to 125C (-67 to 257F)They also come with a five-terminal barrier and a 0.75-inch pass-through hole. A six-pin connector and nine-pin D-Sub connector are also available.

American Aerospace Controls