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Articles from 2005 In October


IPC puts on Boot Camp for lead free requirements

IPC puts on Boot Camp for lead free requirements

The Association Connecting Electronics Industries (IPC) will present the IPC Boot Camp to explain the requirements of the European Union’s RoHS directive. The one-day program will be held December 13 at the Hyatt Regency in Dallas. The program will include presentations by IPC personnel, including Tony Hilvers, VP industry programs, Fern Abrams, director of environmental policy, and David Bergman, VP of technology.

IPC has taken a leadership role in the move to RoHS compliance. The group proposed a standard, IPC-1752, which is designed to help companies communicate the material content of their components. The boot camp is effectively IPC’s beginner course. Ordinarily the association focuses on technical issues involved in the move to green components. “This is intended to be a management briefing,” said David Bergman. “We won’t get into metallurgy. We’ll talk about what’s involved in the legislation and we will explain where companies can go for additional assistance.”

Industry facing late or false RoHS compliance

OEMs may have plenty to worry about as the RoHS deadline nears. Some of their smaller suppliers may not be ready with compliant parts in time for the July 1, 2006 deadline. In other cases it’s worse – suppliers may submit false certificates of compliance, and the OEMs may end up facing fines and embargoed products.

A number of problems continue to plague the electronics industry as it moves to comply with the EU’s RoHS directive. OEMs are asking for compliance data from their component suppliers and they’re getting mixed messages. In some cases, suppliers are simply not ready for RoHS. In other cases, they say they’re ready but they’re not.

The Association Connecting Electronics Industries (IPC) has worked to help companies move toward compliance – particularly with the development of the IPC-1752 standard for communicating compliance information – yet the group finds some companies are so far behind they still need very basic information. So IPC will hold a one-day Lead-Free Boot Camp in Dallas on December 13. “The Boot Camp is for people who are not paying any attention at all,” says David Bergman, IPC’s VP of standards technology. “We’ll talk about what’s involved in the legislation and where companies can go for additional information.”

There are plenty of small suppliers and OEMs that are not prepared for RoHS. But Bergman finds it’s not just the small companies that are scrambling at the last minute to prepare for the July 1, 2006 RoHS deadline. “’We find the level of implementation varies significantly,” says Bergman. “The large companies have paid attention for the most part, but even some of the bigger companies are still missing some critical information.”

Bergman says the most pressing issue is the communication of compliance data. “There are a lot of unanswered questions about data,” says Bergman. “Data is an issue because of the large numbers of components involved. Getting data is a logistics challenge.” He also notes that getting information on the materials content of components is a challenge. “Materials declaration will be a continuing problem from now until forever,” says Bergman. “Not it seems clear that customs will be demanding the content breakdown of products for some time in the future. That will be a lingering problem.”

As the RoHS deadline approaches, it’s becoming clear that many companies – both component suppliers and OEMs will not be compliant on time. “I have talked with companies inside and outside North America who are not convinced they will be ready,” says Bergman. “The concern [among OEMs] is that they’ll get a certificate of compliance [from a component supplier] and it won’t be accurate.”

He says IPC will be telling people at the Boot Camp that they can expect to receive certificates of compliance that won’t be accurate. “You have to decide who you trust,” says Bergman. “Your product could be embargoed and you could be fined. To make sure you comply, you may have to do some testing.”

America ’s Secret Weapon: Better Designs

The trend to shorter product cycles is also creating shorter design cycles, resulting in higher part costs, manufacturing problems, and even warranty issues down the road. Careful up-front work on product design can easily save 50% on total costs, and may even be America’s hidden weapon in winning manufacturing business back from China.  Design News explored these ideas in an interview with Nick Dewhurst, a winner of the National Medal of Technology for his work on design for manufacturability and assembly at Boothroyd Dewhurst, Inc., Wakefield, RI. (www.dfma.com)

How much can you typically improve a product’s cost through careful up-front design?

Dewhurst: That’s the interesting dilemma we face all the time. If you have a project already in production and you do what we do --apply design for manufacturability and assembly (DFMA) techniques and take parts out and look at different materials and processes -- you get about a 50% reduction in product cost.  That same thing is achievable if you do these things early.

How often do companies design the right way and save through careful early design analysis?

Dewhurst: Less than 20% of the time. And that’s probably on the high side. Most US companies today are struggling with time to market.  Faster, shorter design cycles.  And what they perceive at least as the way to solve that problem is hurry up and finish the design. That is the worst thing you can do.  That ends up creating a design that has a bunch of problems in it you spend a lot of time later trying to fix.  If design teams were given more time to investigate other options and explore opportunities for simplification of product structures early in the design phase, you wouldn’t have all of those problems later on.

In all of the years that you have been studying design for manufacturing and assembly are there any common mistakes that you have seen design engineers make?

Dewhurst:  I think it’s the proliferation of lots of simple parts in products. A kind of oversimplified example is that if you want to attach a bracket to the inside of a cabinet, the easy way to design that is to put  four holes in it  and use four bolts four washers, four lock washers  and four nuts. If you’re going to produce that for the next five years, you’re going to pay for that over the next five years by having people put in four bolts, four washers, f0ur lock washers and four nuts.  Now If you had taken a few extra hours, maybe a day, in design you could have come up with some way to put features into sheet metal that secured this bracket to the other bracket without the need for those fasteners. And then for the next five years you are producing that product with the benefit of good design. 

What about failing to design for the benefits of injection molding when people convert from metal?

Dewhurst: That happens all the time. The other thing that happens all the time is that if people are used to designing in sheet metal they are afraid to design plastic snap fits because they don’t know how to do it. There’s a perception that if we put plastic snap fit features on these parts to secure them  together, they’re going to be cheap and they’re going to break and they’re not going to give us the same mechanical characteristics as  metal threaded fasteners. I know that’s not true. If you know how to design plastic snap fits and choose the right materials, you can have very good mechanical properties.  There’s a lack of understanding. The plastics industry has done a good on providing data on plastics materials, but other then a few short items on their Web sites there aren’t a lot of good resources on how to do good injection molded part design. 

To what extent could better design for manufacturing and assembly keeps jobs in the United States?

Dewhurst: It would directly correlate. I told you that people see average savings of 50% on product costs by doing DFMA on their products.  If you’re looking at producing a product in China, you need to save 60 or 70% to make it worth investigating. Interestingly enough, I’ve run into two companies in the last two months that have products in China that they are re-designing and bringing back to the United States for a percentage cost savings. 

What kind of problems did they run into in China?

Dewhurst: Well one of them was a fuel module that was produced at six or seven suppliers in China. So they had to manage this supply chain on the other side of the world and then have the parts shipped back here.  It turns out they redesigned it relying quite heavily on the use of plastics and are producing it  in the United States at about a 15% cost savings.  The second one was a shipping issue. The manufacturer in Chinas was having trouble keeping up with the demand. There also was a problem manufacturing a die casting that was an integral piece of one of these products. So the company needed 1,500 parts a day to keep their line moving. And the Chinese supplier couldn’t produce 1,500 parts a day that were meeting the specs. So they ended up putting the parts on a plane and flying them over every day. And it was costing them something like $35,000 to ship 1,500 of these die castings overnight from China.  Every night.
How much thought went into the original decision to go to China?

Dewhurst: It was one of these off-the-cuff, well if we go to China we can make it there cheaper because their labor is 10 cents a day and we’re paying 50 bucks an hour.  And that’s a real short-sighted view. 

Mark Those Parts

For more than two decades, manufacturers, wholesalers, and retailers have relied on printed bar code labels to control inventory for an endless stream of products. Now, OEMs are rapidly moving to imprint 2D codes directly on parts not just to manage inventory but to enhance data collection for safety, liability and warranty purposes.

Companies in industries ranging from automotive and aerospace to defense, electronics and medical devices typically employ lasers, dot-peening equipment and chemical etching to fix a direct part mark identification (DPMI) on a component. Not only must the mark survive downstream factory processes, but it must also stand up to the wear and tear of rugged environments during the product life cycle.

"You can't put a paper bar code on a piston head," notes Nick Infelise, product manager for Omron, a major supplier of direct part mark (DPM) readers. He adds that the 2D Data Matrix codes used in most DPM applications also allow manufacturers to store far more information than with 1D bar codes—typically 512 characters versus only 15 characters.

Design engineers are getting involved with this growing DPM trend on several levels. First, they must design parts with an eye toward enhancing their readability by machine vision equipment during manufacturing and later at the customer's receiving docks or at repair stations. Frequently, too, design engineers must choose the marking equipment, as well as the hand-held or fixed-mount equipment used to read the marks.

Meanwhile, government and industry groups are pressing for even wider use of DPM, as well as for new specifications to insure that marks meet prescribed quality standards.

Uncle Sam Cracks the Whip

To meet the objectives of the Defense Department's Unique Identification (UID) initiatives, contractors who supply mission-critical components, serialized and repaired equipment, and items costing more than $5,000 are now required by contract to mark and verify DPM codes on these parts.

"The UID is fast becoming the law of the land for defense contractors," says John Agapakis, senior VP for RVSI Acuity CiMatrix, a pioneer in the Data Matrix reader field. "Contractors that don't mark their parts won't get paid."

To help manufacturers cope, RVSI Acuity launched a program early this year to educate engineers in the defense industry on how to comply with the UID requirements. The effort involves a site visit, briefings to engineers, IT, quality control, and contracts personnel, and a review of potential parts requiring a mark. RVSI then comes back to the company with recommendations on equipment and processing steps needed to meet DoD's requirements.

"Many engineers are just finding out about UID," says Tim Pastore. "There is a real hunger for information."

RVSI Acuity also publishes a UID newsletter with FAQs and recommendations on marking and reading methods and is holding free online training seminars on UID and Data Matrix verification issues on a dedicated website (http://www.UIDsupport.com).

Early this year, the company introduced a UID compliance kit that helps engineers meet MIL-STD-130L for direct part making. The kit shows how to determine whether the data elements in the Data Matrix mark are properly formatted, and it provides verification tools to insure that the UID mark is legible for the life of the product. Among the equipment included in the kit: high-performance Data Matrix reader/verifier with integrated lighting, optics, CCD imager, processor, digital I/O, communications and networking ports.

John O'Brien, VP for UID systems, notes that it is important for engineers to distinguish between regular reader stations—either fixed or hand held—that read parts during the manufacturing process and verification stations, which are located adjacent to where the part is originally marked. The verification station typically is positioned perpendicular the part, is equipped with more processing power, and takes more measurements. At this station, companies can verify that marks meet industry standards, as well as spot instances of degrading mark quality. For example, inconsistencies in the shape or size of dots may indicate wear on the tip of a dot-peening stylus.

Pressure from Industry Giants

While RVSI predicts that the military applications may soon account for 50 percent of the DPM applications it serves, another major reader supplier—Cognex—also sees rising demand in automotive, aerospace and electronics components. "The need for cradle-to- grave traceability of critical parts is the big driver," says Justin Testa, senior VP of the Cognex ID Products business unit. Testa notes, for example, that a good DPM system can be a big cost saver for auto companies during recalls, when they can sharply reduce the number of cars needing to be checked at dealers because of the ability to trace specific parts back to Vehicle Identification Numbers.

In addition to the major OEMs themselves, major industry organizations such as the Automotive Industry Action Group and the Air Transport Association have published guidelines for Data Matrix. Where there is no specific standard, Data Matrix ECC200 is recommended. This ANSI code is the most widely supported for DPMI applications involving metal, glass, ceramic, or plastic materials.

Testa says that engineers can expect to pay from $2,000 to $3,500 for the machine vision system that makes up a fixed-reader station in an automation line. However, a single part may need to pass through several readers during a manufacturing operation. The more powerful verifier stations, which are often bundled with marking equipment, can cost as much as $10,000. "You are not going to get read rates on direct part mark codes approaching 100 percent with a $200 hand-held reader," says Testa.

Readers also are becoming easier to operate and program. Omron's V530-R2000 controller, for example, offers automatic setup and controls two tiny CCD cameras—often with a choice of integrated lighting options to handle different surfaces. A hand-held keypad provides access to the controller's systems menus for needed adjustments, and a display unit outputs the results as parts pass through the system. Omron Product Manager, Nick Infelise, notes that the R2000 is especially popular in semiconductor and LCD production, where managers are looking for automated, high-volume solutions that require few adjustments.

The Push for Quality

With DPMI rapidly growing for parts ranging from wafers and printed circuit boards to engine parts and medical devices, attention is increasing to ensure that that marks are of sufficient quality to be easily read throughout a part's lifecycle. Manufacturers of marking equipment and readers are stressing the importance of installing verification stations that spot degrading mark quality as early as possible so that companies can meet their own internal quality goals.

AIM Global, a worldwide trade association dedicated to automatic identification, is also working with industry to draft a new 2D DPM verification standard, which could be in place by the end of 2006. The existing print quality standard, ISO 15415, was developed for paper labels and has limited application to direct part marking, according to AIM President Dan Mullen.

"There's no question that direct part marking is growing," says Mullen, "and the entire industry will benefit if we can establish criteria for measuring the quality of these marks. And if a mark meets the criteria, then the equipment better be able to read it."

Web Resources
//For more information check out these links//
RVSI Acuity CiMatrix UID compliance kit:
http://rbi.ims.ca/4417-505
Cognex ID products:
http://rbi.ims.ca/4417-506
Omron ID products:
http://rbi.ims.ca/4417-507
Microscan ID products:
http://rbi.ims.ca/4417-508
AIM Global:
http://rbi.ims.ca/4417-509
 

16-bit Controllers

In some ways, 16-bit architectures have turned into the forgotten stepchildren of the microcontroller world. When planning strategies, some of the world's biggest microcontroller makers have simply stepped directly from 8-bit to 32-bit, presumably because they believe there's too much overlap between the three markets.

Not so for Microchip Technologies, Inc. and Texas Instruments, which over the past 60 days have rolled out substantial new 16-bit product lines. Two weeks ago, Microchip announced 49 new microcontrollers and digital signal controllers, all of which are based on 16-bit architectures. And on August 30th, Texas Instruments made a similar unveiling, announcing plans to add over 50 new 16-bit devices over the next 18 months.

"There's a notion in the market place that 16-bit is being passed over and everyone's going to 32-bit," notes a Microchip spokesman. "But our latest introductions definitely counter that notion."

Indeed, there's good reason to believe that 16-bit is alive and well. Recent statistics from market watchers Gartner Dataquest, WSTS (World Semiconductor Trade Statistics), and Forward Concepts indicate strong market growth for 16-bit. From 2003 to 2004, they say, 16-bit grew 21 percent, approaching the 8-bit market in overall size.

"By next year at this time, we expect the 16-bit market to top $5 billion a year," says Sumit Mitra, vice president of Microchip Technologies Digital Signal Controller Division. "It's still a good market to be in."

TI bets on low-power designs

The low-cost of TI's MSP430 ultra-low power microcontroller platform makes it a candidate for applications moving up from 8-bit to 16-bit, say TI engineers.

"It's definitely a 16-bit RISC architecture, but because of its cost, the MPS430 is competing directly against the 8-bit market in some cases," notes Mark Buccini, marketing director for TI's Advanced Embedded Controller Group.

The 14-pin, 16-MIPS MSP430F20 (one member of the MSP430 family), for example, cost $0.49 per 100,000 units, while operating at an active current of just 200 µA/MIPS.

All members of the MSP430 platform, however, are designed for low-power usage. TI engineers say that devices offer better battery utilization characteristics and longer standby, enabling them to conserve power in high-performance products.

The company says it's targeting the new technology at metering systems and handheld monitors, such as blood glucose monitors, as well as at a host of other applications. For more information about TI's MSP430, go tohttp://rbi.ims.ca/4399-522.

Microchip aims for performance

To meet the demand for 16-bit architectures, Microchip Technologies is rolling out three 16-bit families: the low-end PIC24F; the more powerful PIC24H; and the dsPIC33 digital signal controller. Pricing for the PIC24F starts at $4.55 in quantities of 10,000, while the PIC24H starts at $5.16, and the dsPIC33 begins at $5.43.

For its PIC24 family, Microchip is unveiling 22 devices, offering up to 40 MIPS performance, 16 Kbytes of RAM, and 256 Kbytes of Flash. Similarly, the company's dsPIC33 operates at 40 MIPS with 64 to 256 Kbytes of Flash.

Microchip, which has made its name in the marketplace with its 8-bit microcontrollers, says it expects some of its 16-bit customers to move up from the 8-bit world.

"Some grassroots applications, such as home security systems, are naturally going to migrate up to 16-bit over time," notes Sumit Mitra, vice president of the Digital Signal Controller Division at Microchip. "If you're running out of memory or performance, it's a natural step up." For more information on Microchip's PIC24 family and dsPIC33 family, go to http://rbi.ims.ca/4399-523.

Electronics

Lighting contactor

For branch circuits

Engineered to reduce energy consumption, the Allen-Bradley Bulletin 500LC is a 20A multi-pole lighting contactor designed for branch circuits. It provides users greater design flexibility and customization options. It requires a momentary applied current to either open or close and isn't dependant on a continuous control voltage to maintain its position. It is designed for easy installation in both new and retrofitted environments. Rockwell Automationhttp://rbi.ims.ca/4399-576

PC board

1 GHz version

The BAB (Basic Automation Board) 760 is now available in a 1 GHz version, featuring state-of-the-art CPU design with PCI architecture. It is designed for requirements associated with medical applications, telecommunications, and industrial automation. It is particularly ideal for versatile industrial control applications, and it can be easily expanded using a PMC module. A PMC extender card permits one or two PCM modules to be fitted. American ELTEChttp://rbi.ims.ca/4399-577

Shaft speed sensor

Stainless steel housing

The SpeedTalker DN-BH shaft speed sensor provides DeviceNet connectivity, easier installation, and a compact NEMA 4×-rated stainless steel barrel housing. It is engineered to operate in a range of demanding industrial environments. It provides measured shat RPM, along with the status of up to four under/over speed alarms over a DeviceNet network. Electro-Sensors Inc.http://rbi.ims.ca/4399-578

Sensors

Oversized status indicator

The WORLD-BEAM QS30 Series sensors are available in standard 10 to 30V dc or 12 to 250V ac universal voltage formats. They feature a 30- mm threaded barrel or side hole mounting option, IP67 sealed housing with EMI/RFI protected circuitry, and an oversized status indicator for clearer visibility. They are ideal for a variety of applications, including packaging, materials handling, wood processing, automotive, and pharmaceutical industries. Banner Engineeringhttp://rbi.ims.ca/4399-579

Liquid level sensor

Non-invasive

Designed as a unique, non-invasive ultrasonic sensing solution, the levelprox sensor provides accurate point level detection of liquids through metal container walls. The product mounts to the outside of a container and is ideal for high pressure, hazardous, or sterile applications. It uses a simple teach button to program empty and full conditions for detection of liquid. The product is available in two housings: T50 and M30. TURCKhttp://rbi.ims.ca/4399-580

CD catalog

Easy to navigate

The company's B0010 Sensors and Connectivity CD combines its two largest catalogs into one CD. The 1,200 pages, designed in PDV format, are easy to navigate and store, according to the company. Bookmarks and quick links enable users to locate information and move from catalog pages to menus, to selection guides, with the click of a mouse. It can be used as a tool to print off portions of the catalog, or to separate individual pages and send them to other users. TURCKhttp://rbi.ims.ca/4399-581

Search function

Online

The company's online parametric search function is designed to enable users to select specific relays or switches based on a range of characteristics. The search function is available for solid-state relays as well as electromechanical relays and coaxial switches. Users can choose options from drop-down menus from a list of parameters, and the engine indicates how many devices are available that meet the selected criteria. Teledyne Relays http://rbi.ims.ca/4399-582

ADCs

Reduces board space

The AD9237 analog-to-digital (ADC) converter is a 12-bit monolithic, 20/40/65 msps ADC that consumes 40 percent less power than comparable devices, according to the company. It is available in a 5 x 5-mm package, and combines small size and low power to reduce board space in portable instrumentation, ultrasound, high-end imaging, digital still camera, scanner, and low-power communications applications. The product consumes 190 mW of power at 65 msps, 135 mW at 40 msps, and 90 mW at 20 msps. Analog Deviceshttp://rbi.ims.ca/4399-583

Concentrator system

Housed in industrial metal

Engineered to convert a HART digital signal to a serial (RS-485) MODBUS RTU communication protocol, the HCS HART concentrator system permits up to 16 smart HART-capable transmitters and valves to interface directly with MODBUS-based monitoring and control systems. The product interfaces all HART parameters to MODBUS, including the ability to monitor primary and non-primary process variables from smart multivariable mass flow, pressure, PH, and temperature transmitters, among others. It is housed in an industrial metal and RFI protected housing that snaps on to standard DIN-style rails. Moore Industrieshttp://rbi.ims.ca/4399-584

Expansion boards

Eliminate alias frequencies

The company's signal-conditioning expansion boards for its DAP boards are designed to make it easy to implement signal conditioning in data acquisition systems. MSXB 064 and MSXB 065 provide differential instrumentation amplifiers with optional sample-and-hold circuits and jumper-selectable gains of 1, 5, and 25. MSXB 065 also includes fourth-order anti-alias filters. They can eliminate alias frequencies from acquired data, and they slot into a backplane in a standard industrial enclosure. Microstar Labs Inc. http://rbi.ims.ca/4399-585

Electrolytic tilt sensor

Accurate

The company's single axis linear output electrolytic tilt sensor features a ±30 minimum angle ranges, &0.05-arc second resolution and &0.5-arc second null repeatability. It also features long-term stability over its angle and temperature range. The product is ideal for a variety of applications, including those requiring ultra high accuracy, excellent null repeatability, and a linear output. Other applications include construction laser instruments and transits, aircraft avionics, geophysical monitoring, machine tool leveling, and medical positioning or monitoring. Fredericks Co.http://rbi.ims.ca/4399-586

Robot system

Efficient

The SR Mate 100iB is integrated with molding machine control. It is available as a fully integrated, ready-to-run option on 55- and 110-ton machine models. The system requires no installation time and offers a total height of 2,470 mm when mounted on the company's Roboshot 110. It features "cat-quick" part removal stroke of 0.5 sec/700 mm, and it is ideal for low-ceiling buildings and clean rooms. Milacronhttp://rbi.ims.ca/4399-587

Laser mirrors

No coating

The company's Molybdenum Mirrors are made from molybdenum, which is an intrinsically hard material that doesn't require coatings to achieve >98.1 percent average reflection at 10.6 µm at 45 degree AOI, with &1.9 percent absorption and scatter. They are suitable for use with industrial lasers that range from 20W up to kilowatts in power. They are available in 1/4 to 1 inch diameter sizes for low-power lasers, and 1 to 3 inch diameter sizes for high-power lasers. Laser Research Opticshttp://rbi.ims.ca/4399-588

Indicator light

Sealed housing

The EZ-LIGHT smart indicator lights are water- and oil-tight sealed units that have colored lights which indicate the status of a machine or process. They were developed to replace cumbersome and stack lights with a single, compact unit that is sealed and IP67 rated. It features a rugged, solid-state design with no bulbs to burn out or replace. It is available in three configurations: three-color general purpose, multicolor seven-function, and a style that acts as a large remote indicator for the company's EZ-SCREEN®. Banner Engineering Corp.http://rbi.ims.ca/4399-589

Cam switches

Reliable

The Series 20 Cam Switches feature double-break, silver-plated contacts housed in rigid thermostat plastic for long, reliable life. The product's versatility enables various configurations with up to 12 decks and up to 12 positions. They are mounted on 3-inch centers, thus requiring less space on control panels. The products are offered in three basic configurations: standard, lighted, and modular. Electroswitchhttp://rbi.ims.ca/4399-590

Embedded PC

High performance

The CX1020 embedded PC features a direct connection for EtherCAT I/O terminals. It has a 600 MHz Intel Celeron M CPU; it uses Compact Flash as its boot and memory medium, so it needs no rotating media. It is engineered to provide the same functionality as large industrial PCs, enabling up to four virtual IEC 61131 CPUs that can be programmed with up to four tasks each. TwinCAT functionalities are available for motion control applications. Beckhoff Automationhttp://rbi.ims.ca/4399-591

I/O and pneumatic solution

Compact

The IE2808 IP-Link Extension Box is designed as an IP67-rated I/O and pneumatic solution for direct mounting on machines. It provides 16 digital 24V dc outputs at a low price per channel. A 25-pin D-Sub connector offers a cost-effective connection to the outputs. Each channel is designed to be short-circuit-proof and offer diagnostic capabilities. It is ideal for direct connections to valve terminals in wet and dusty industrial environments. Beckhoff Automationhttp://rbi.ims.ca/4399-592

Laser line sensor

For sectional profile scanning

The EyeCON is an Ethernet-ready UDP protocol Class II laser line sensor that can scan up to 150 points across a horizontal measuring line. It processes more data than many other scanning systems by combining the advantages of digital technology, image processing, and laser line projection. Features include on-the-spot measurement of materials and equipment variations across multiple dimensions, tighter production control for optimum uniformity and product quality, and increased operator control for greater throughput and reduced waste. LMI Technologieshttp://rbi.ims.ca/4399-593

Switching power supplies

Miniature

The M-Series of miniature chassis-mount medically approved switching power supplies feature a range of 5 to 30W output power. All models are engineered to accept universal input over the range of 85 to 265V ac, and they provide single, dual, and triple output configurations with voltages from 3.3 to 24V dc. They feature a space-saving modular design and are fully approved to IEC-601-1 low leakage specifications for use in medical/dental instrument and system applications. Astrodynehttp://rbi.ims.ca/4399-594

Computer-On-Module

Delivers better performance

The ETX-P3T and ETX-P3Tx Computer-On-Module (COM) designs are engineered to deliver better performance while maintaining reasonable power consumption levels (less than 10W). The first uses the i815E chipset and powerful Intel Celeron processors. It features up to 32 Mbytes of dedicated graphics memory and is ISA bus supported. The second uses Intel Celeron ULV processors paired with Intel Northbridge and Southbridge chipsets. It features up to 512 Mbytes SDRAM SO-DIMM memory. Kontronhttp://rbi.ims.ca/4399-595

RF cable connectors

High durabilityThe SMA subminiature RF cable assemblies are available with straight or right angle terminations. They feature high durability, compact semi-precision connectors, and use 0.085 and 0.141 inch semi-rigid cables and standard flexible cables. The products mate with the company's line of MMCX, MCX, and SMA connectors. Prices vary by size and configurations. Samtechttp://rbi.ims.ca/4399-596

Firmware

Provides full support

The company has released R2.0 of its IPM Sentry Shelf Management firmware, which provides full support for the company's IPM Sentry ShMM-500 and ShMM-300. This enables users to take advantage of the 7× processor speed improvement. It includes support for reliable remote upgrades to all ShMM-500 resident firmware. When new firmware is downloaded, it is provisionally loaded into flash memory and started. If problems occur during validation, the hardware automatically falls back to the previous stable copy of the firmware. Pigeon Point Systemshttp://rbi.ims.ca/4399-597

Circuit breaker panel

Uses minimal rack space

The DPB2U-AB dual bus circuit breaker panel provides distribution and overload protection for up to 18 dc circuits and will be of great interest to designers putting sizeable telecom systems together. Using minimal rack space, the panel can be configured for 12, 24, or 28V dc telecom systems with either positive or negative ground. They distribute up to a total of 300A of load current for each A or B bus, with each bus having up to 9 circuit breakers. Unipowerhttp://rbi.ims.ca/4399-598

Barrier diode

Extends battery life

Featuring typical and maximum reverse current ratings at 30V of 1µA, the ZLLS350 Schottky barrier diode is designed to extend battery life in a variety of applications. It features a very low forward voltage specified at a typical 380 mV for a forward current of 30 mA. This enables the miniature SOD 523 device to offer an efficiency that is greater than larger packaged devices. It also has an increased maximum operating temperature. Zetex Semiconductorshttp://rbi.ims.ca/4399-599

Rotary Sensors

12-bit resolution

The RSC3700 family of non-contacting rotary sensors is engineered to provide 360-degree absolute angle measurements with 12-bit resolution. Measurements are referred to a mechanical index point, providing retention of position in the event of a power failure. A microprocessor incorporated into the sensor allows a custom output characteristic curve to be preprogrammed for a specific application. It has a resolution of ± 0.09 degrees. Novotechnikhttp://rbi.ims.ca/4399-600

Laser technology

Smaller thickness

The LT-9000 Series of laser confocal displacement meters makes it possible to achieve accurate 0.01-micron thickness measurements on transparent objects using a single sensor head, even when target surfaces are wet, angled, or irregular according to the company. Multiple measurement modes include profile measurement, transparent object thickness measurement, angle measurement, and cross-sectional area measurement. The product incorporates a built-in CCD camera that provides a microscopic image of the target surface. Keyence Corp. of Americahttp://rbi.ims.ca/4399-601

USB controller

No graphics card required

The ArtistaUSB controller makes it possible for users to control VGA and SVGA TFT displays via a standard USB interface with no graphics card required. The user needs to just plug the controller into the USB interface on a computer. It also enables users to control more than 100 displays with different content from a single PC, SBC, or microcontroller. Apollo Display Technologieshttp://rbi.ims.ca/4399-602

Motion control card

4-axis

The NPMC6045A-4104 is a 4-axis PC/104-bus motion control card. It enables the user to control stepper motors and/or digital servomotors. It incorporates a PCL6045A advanced ASIC motion control chip as part of its compact design. It also comes with MS-DOS, C source code, programming library, and Windows 98/XP/NT/2000 DLL for VB/VC. Ideal applications include semiconductor, robot, or medical instrumentation manufacturing. Nippon Pulsehttp://rbi.ims.ca/4399-603

Switching power supplies

With soft-start circuitry

Engineered to meet the space and performance needs in low- to moderate-power telecommunication, industrial control, and embedded systems applications, the SP-320 Series of high-density enclosed switching power supplies provide output power of 320W. All models accept universal input from 85 to 265V ac with active power factor correction to 0.98. All feature soft-start circuitry. Astrodynehttp://rbi.ims.ca/4399-604

DMOS devices

Reuse design IP

The company has incorporated high-power lateral DMOS devices into its Polar35 process family. The Polar35 LV process features modular 5V analog CMOS, as well as 7 and 12V power device suites. It also employs a modular device and mask approach that gives users the ability to optimize their design for performance versus cost. Users can also reuse design IP across many product families. PolarFabhttp://rbi.ims.ca/4399-605

The Potential of MEMS

What kind of growth are we seeing for MEMS technology? The latest forecast from the Yole Development research firm is that total sales in the MEMS market will reach $5.4 billion this year and will grow to more than $7 billion in 2007. That's a 15 percent annual growth, and some new areas of growth may not yet be reflected in this forecast.

Which sectors of MEMS are driving this growth? Some of the biggest sellers on the market are inertial devices. Applications range from stabilization and navigation to steering and traction control. Also very significant are micromirrors, such as those produced by Texas Instruments, which are used in projection devices and flat-screen TVs. For traditional MEMS devices, such as pressure sensors, we will see big growth in tire-pressure monitor applications. RF applications are still another area to watch. Beyond the scope of current forecasts are new uses of MEMS as monitoring devices in medical care, as well as in analytical instruments for industry. MEMS devices will move the central analytical lab to the point of use. Such applications depend on the cost, size, and ease-of-use advantages inherent in MEMS.

What new applications particularly impress you?A good example of MEMS' potential to put high performance in a small form factor is atomic clocks, which have wide applications in communications and positioning systems. I'm also impressed with the ability of MEMS to put very sophisticated instruments on a chip, such as gas chromatographs, mass spectrometers and so on. You will also see MEMS in neural probes, artificial organs, and in pressure sensors for devices that treat heart disease. MEMS will be a great enabler for pervasive monitoring in all sorts of applications. Before long, you will have cell phones with MEMS pressure sensors and magnetic sensors for location, orientation, and altitude.

With the top 10 MEMS suppliers accounting for 90 percent of sales, isn't it very difficult for start-up firms? The MEMS Industry Group (MIG) is working this problem from many angles. Having an adequately trained workforce is key. You don't want to create an industry relying only on Ph.D.s. MEMS education programs below the Ph.D. level are being created in many universities. MIG, working with DARPA, also has done research on the costs and time required to bring a new MEMS device to market-as well as estimates on prices for MEMS products. The goal is to share that information with existing small companies and potential start-ups so they can develop sound business plans.

How will the boom in nanoscale research affect MEMS? Nanotechnology research will be a fantastic enabler for MEMS and help it reach full potential. Work in nanatechnology will yield new materials that will foster development of new chemical and biological sensors-two areas with tremendous opportunity for growth. You will also see new light sources integrated with MEMS devices as another byproduct of nanotechnology. As a result, I'm convinced that the next 20 years will bring many more exciting developments in MEMS than we've seen in the past 20 years.

Cleopatra Cabuz is Director of Global Technology at the Sensors Laboratory of Honeywell's Automation and Controls business unit.

Re-wiring the Body

It's the stuff of science fiction: a bionic arm that slips onto the stub of an amputated limb and supplies all the movement and dexterity of the real thing. Movie characters since the days of Luke Skywalker have been attaching them, gazing hopefully, then wiggling their fingers in a modified victory dance to show that their artificial limbs were every bit as good as nature's original.

Film fancy? Maybe not.

At the Rehabilitation Institute of Chicago, physicians earlier this year laid the foundation for such technology when they strapped Jesse Sullivan's new arm and shoulder into place. Sullivan, a Tennessee power company lineman whose arms were amputated after he was electrocuted on the job, suddenly had an artificial limb that allowed him to rotate his wrist and upper arm, bend his elbow, grip with his hand, and, incredibly, feel. And like Luke Skywalker, Sullivan required just a few minutes of learning to adjust to the new limb, mainly because it used a neural wiring scheme similar to nature's own.

"What's interesting about Jesse is that he simply does what he always did prior to the accident," notes Bill Hanson, president of Liberating Technologies, Inc., the company that made Sullivan's digital arm. "If he wants to lift something off a table, or reach for something over his head, his thought process is exactly like anyone else's." Hanson adds that because the prosthesis is so schematically similar to a real arm, Sullivan learned how to use it in about 90 minutes.

"There's a lot happening under the hood here," adds Kevin Englehart, associate director of the Institute of Biomedical Engineering at the University of New Brunswick and a contributor to the design. "But for the user to learn, it requires just a quick calibration."

Re-wiring the Body

Indeed, a great deal is happening "under the hood" of Sullivan's prosthesis, but the ones who most effectively grasp its advantages are those who have used conventional prostheses. Even the best of today's powered versions can't execute the direct brain-to-hand technique employed in Sullivan's unit. Rather, they require

 

Sullivan's arm-and-shoulder system includes motors for the elbox, shoulder, humerus, wrist and hand.

users to relearn the simplest motions. People who have lost a hand, for example, might use their biceps or triceps muscle to initiate powered hand movement. Moreover, many such prostheses can't execute a quick series of motions, requiring instead that users step through a sequential parade of muscle contractions to, say, simultaneously reach and turn.

"When you re-wire the arm so that the biceps controls the hand, it takes a lot of re-learning for the user," Hanson says.

Indeed, that convoluted re-wiring process was, at least in part, the motivation behind Sullivan's new arm. Todd Kuiken, a physician who holds a Ph.D. in biomedical engineering, first conjured up the concept while reading a medical journal more than 20 years ago. His idea was to use so-called "nerve reinnervation" to gain additional control signals for a prosthesis. That way, the prosthesis could take advantage of existing nerves, even if the limb associated with those nerves had already been amputated.

While there's a simple beauty to that concept, Kuiken learned over the years that connecting nerves directly to prosthetic devices was unrealistic. Signals in the human nervous system, he found, were far too weak to control such devices. To solve the problem, Kuiken decided to connect the nerves instead to usable bands of muscle, which could serve as amplifiers for the weak signals coming from the nerves.

As best as anyone can tell, Kuiken's method is unique in the annals of medicine, and it is opening up possibilities unlike any in the recent history of prosthetics. Today, he is combining his reinnervation scheme with myoelectric sensor technology and so-called "digital limbs" to enable Sullivan to accomplish tasks that would have been impossible in the past.

"With this arm, Jesse can take off his baseball cap and put it back on," says Kuiken, who serves as the director of amputee programs and associate dean at the Rehabilitation Institute of Chicago. "He can reach up and take things from a cupboard. He can grasp and turn a doorknob."

Moreover, Sullivan can do all those tasks, especially complicated ones such as grasp-and-turn, with merely a vague notion of desire. His conscious thoughts travel from his brain, through his nerves, and into a digital arm that interprets them.

Incredibly, Sullivan is also regaining a sense of feeling. "If you touch his chest, he feels it in his 'hand,'" Kuiken says. "Ultimately, that gives us a portal to give him true sensory feedback. We're working on the idea of him being able to feel what he is squeezing."

Motors That Respond to Thoughts

Making all of that happen, however, has been a long, laborious task for Kuiken and other researchers around the world, as well as for contributing suppliers, such as Liberating Technologies. The latest version of Sullivan's arm, outfitted for him this past February, contains a motorized elbow, shoulder, wrist, humerus, and hand.

 

Boston Arm's 2x6-inch printed circuit board incorporates six drives for the arm's six motors

In all, the system uses six motors, including one brushless DC unit in the elbow built by Liberating Technologies, two in an artificial hand created by the Keshing Co. of China, one motor in the wrist rotator built by Otto Bock Healthcare (Germany), one brush-type motor in the humeral rotator constructed by Northwestern University, and one in the artificial shoulder joint designed by engineers at the University of Strathclyde (Scotland).

All of the motors respond directly to Sullivan's thoughts. The device's operation begins with a conscious command from Sullivan. If he thinks, for example, about closing his hand, the command from his brain travels in the form of a low-voltage electrical current along the nerve, to a band of muscle in his chest. The chest muscle is key for Sullivan, because it is the locale at which various nerves from his amputated hand and arm have been reattached, or re-innervated, during previous surgery. Because that portion of Sullivan's hand nerve is still intact, it is able to deliver the "close hand" command to the chest muscle. The chest muscle therefore contracts, and a myoelectric sensor atop Sullivan's skin detects the contraction (muscle contractions naturally emit an electric field), sends it to an amplifier and then to a digital signal processor (DSP) located in the Boston Digital Arm. The arm's DSP interprets the signal, then sends a command to the hand motor, which closes the hand.

All of this happens in the blink of an eye. For engineers, the challenge is to keep the signals moving at a rate that's roughly comparable to the natural rate of travel through the human body, so there isn't a noticeable lag time between Sullivan's thoughts and his arm movements. To do that, the signals are sent from the myoelectric sensors to a 1.75-inch diameter interconnect board in the arm and through to a differenetial amplifier, before reaching the DSP. The DSP, operating at 20 MHz, sorts through one or more signals at a time, then sends commands to the appropriate motors.

At the end of all this activity, the arm's response must not only be quick, but accurate as well. If Sullivan wants to move in a powerful fashion, the bionic arm must respond in kind.

"It's got to be linear," notes Richard Weir, a research scientist at the Jesse Brown VA Medical Center, professor at Northwestern University's Biomedical Engineering Department, and designer of the humeral rotator. "Contract the muscle hard; create a bigger signal; drive the motor faster."

Interpreting Neural Signals

Understanding the body's signals, however, may be the most daunting task of all for engineers. For that, the DSP must be fast and capable, and the on-board software must be able to determine which motor, what direction it should turn, and how fast.

To deal with the hardware challenges, Liberating Technologies employed a Texas Instruments (TI) C2000 DSP, rather than a conventional microcontroller, because DSP provides greater number-crunching capabilities. "DSP gives more advantages in this case, mainly in the number of motors it can control, as well as in packaging and integration," says Chris Clearman, C2000 business development manager for TI.

Making the decisions, however, was a matter for the software running on the C2000. Determining which motor to run was probably the simplest of those decisions, since motors have dedicated muscles assigned to them. A 2×6-inch printed circuit board inside the Boston Digital Arm incorporates six motor drives, each connected back to a separate band of muscle. For example, one band of chest muscle might command wrist pronation, while another commands hand grasp.

The task of deciding which direction and how fast to run the motors, however, is a stickier issue. To do that, engineers at the University of New Brunswick worked with Kuiken to implement pattern recognition algorithms that "look" at the incoming signals from the electromyogram (EMG) sensors atop the skin.

"The EMG signals are much more random than what you typically deal with in engineering design," notes Englehart of the University of New Brunswick. "It makes measurement very difficult."

Still, engineers have found ways to reliably interpret the signals. Englehart's software does this by looking at the signal patterns produced by Sullivan's muscles during prescribed tasks, and then learns from them.

"When he tries to elicit control of an elbow, wrist, or hand, the system looks at the muscle activity, and then uses neural networks to learn from those motions," Englehart says.

Based on those patterns—and based on the ability to discriminate between legitimate activity and electrical noise—the system primarily uses signal amplitude to determine motor force. It also determines which of 25 arm actions are desired within an accuracy of about 96 percent, Englehart says. Eventually, researchers hope to draw more information from various signal characteristics (particularly frequency), and then use them to map out more complex arm motions.

"There's a ton of data in there and we're still finding ways to sort it all out," Kuiken says. "Eventually, we hope to use it to determine what kind of hand grip Jesse might want to do, whether it's a fine pinch or a power grip or a key grasp."

Enhancing the Concept

For now, Sullivan's arm offers the advantage of simplicity. Sullivan doesn't need to press a button to operate the device, nor squeeze a near-by muscle that would ordinarily be unrelated to the task at hand.

"This arm offers two advantages," Kuiken says. "It gives more control information and it's more intuitive for the user."

For now, Kuiken plans to add more capabilities to Jesse Sullivan's prosthesis. He wants to enhance Sullivan's sense of touch and wants to provide dexterity to his fingers. He says he has noticed that the skin around the reinneverated areas of his chest muscle have developed sensation, and he would like to use that to provide more feel in the hand and arm. Moreover, he believes that in the future he can add more degrees of freedom to the hand and eventually create fingers that wiggle.

"We are definitely moving toward being able to control digits," he says.

"It's the same as Luke Skywalker, except that Jesse does not have the dexterity," adds Hanson. "But it will happen some day, and it won't be too far in the future."

Web Resources
To learn more about muscle reinnervation and Jesse Sullivan's prosthetic limb, try these sites
To see a video of Jesse Sullivan's arm at work, go to
http://rbi.ims.ca/4399-560
To read a paper on targeted muscle reinnervation, co-authored by Kuiken, go to
http://rbi.ims.ca/4399-561
To learn more about the Boston Digital Arm, go to
http://rbi.ims.ca/4399-562

Solid State Relays Increase System Reliability

Manufacturers of satellites, satellite launch vehicles, and other high reliability equipment face many challenges when designing electromechanical relays (EMR) into their systems. Preventing false relay operation from shock and vibration requires additional safety considerations. In addition, "hash filters" are sometimes necessary to debounce the contacts, which add space and weight. However, solid state relays (SSRs) are immune to the shock and vibration levels normally encountered in the application and do not need contact filters. As a result, the use of SSRs in place of the mechanical type leads to a more reliable end product. However, the transition to SSRs requires understanding a number of new parameters to ensure proper operation.

Changes With SSRs

Various electronic components in an SSR take the place of the electromechanical elements in a mechanical relay. The SSR uses a MOSFET in place of mechanical contacts to eliminate contact bounce. However, if there is any significant power dissipation involved, proper heat sinking will be necessary to ensure safe operation (see sidebar, MOSFETS Make it or Break it).

The traditional relay uses an electromagnet in conjunction with other mechanical components to affect contact actuation. In contrast, the SSR employs a photovoltaic isolator (PVI). As a minimum, a PVI consists of an LED and a photovoltaic array. When sufficient current flows through the LED, the light output falls on the array, generating a voltage that charges the FET gate. This turns on the SSR. To ensure that the MOSFET turns off when required, there is a gate discharge circuit present. In addition, an input buffer is also included allowing direct interface to logic devices.

 

The physical separation between the LED(s) and the array in a SPDT (Form C) dc SSR provides at least 1000V of isolation between the input and the output of the SSR. The enhancement mode MOSFET requires a gate voltage to turn it on and the depletion mode requires a gate voltage to turn it off.

In relay terms, this particular configuration is a Single Pole, Double Throw (SPDT) or a "Form C" relay. Since the MOSFET has a body diode, this arrangement does not block current flow in both directions, limiting its use to dc circuits. For ac usage, an additional MOSFET in series, source-to source, blocks current in both directions.

With its inherent isolation, the SSR can drive either the high side or the low side, or even between sides, as in a solar array battery charger. In this application, an additional isolation diode prevents battery discharge into the solar array through the FET body diode when the charger is off. Another way to accomplish this with less power dissipation is to use an ac SSR (or to use both channels of a dual dc SSR, and connect them in series, source to source) in place of the dc SSR/diode combination.

SSR Switching Times

EMRs do not switch very fast, perhaps in the neighborhood of 5 to 20 msec. The switching time of a normally constructed SSR is in the same ballpark, due primarily to the poor current transfer ratio of the PVI. The PVI output current has to charge the gate capacitance of the output FET and this takes time. For most applications, this medium speed response is acceptable. For faster switching, multiple "hot" (or so-called fast) PVIs can be used. These produce more current to charge the FET gate, resulting in a faster turn-on.

In other applications, however, system designers may be concerned with dV/dt and/or dI/dt. Keeping these values low helps keep electromagnetic interference (EMI) at acceptable levels. For instance, many satellites have multiple heater wires that keep the electronics and/or sensors at proper temperatures. A fast dV/dt on these wires could broadcast noise into internal electronics dictating the need for slower rise times.

To accommodate these EMI requirements, SSRs are constructed with additional internal circuitry that keeps dV/dt and dI/dt at "controlled" (i.e., slower) levels, helping to reduce system RFI and EMI. For example, a fast 100V, 1.5A octal SSR has a maximum 2 msec rise time and 9.5 msec fall time. The controlled version's specifications for these same parameters are 3 msec and 15 msec, about 1.5 times longer. The fast units have a maximum input supply current of 25 mA for a 1A output compared to a maximum of 15 mA for the controlled units.

A consequence of this controlled (i.e. slow) switching is that the MOSFET transitions its active region slowly. If turn-on transients are expected, for example due to a capacitive load, an analysis must be performed to ensure that the design does not violate the MOSFET safe operating area (SOA) limits (refer to sidebar). Fortunately, heater wires are mainly resistive, and therefore do not have a turn-on transient issue.

Surge Current Limiting

Solid-state devices are susceptible to failure with excessive current. One method of limiting the current surge uses a small resistor in series with the load. A second SSR can bypass the current limiting resistor if proper circuit operation does not permit leaving it in the circuit permanently. The second SSR turns on slightly delayed from the main load SSR. Some SSRs have a multi-purpose input circuit for automatically bypassing the current limiting resistor. The current limiting resistor for the second (bypass) SSR sets the input LED current in the 10 to 20 mA region.

Other applications may require a faster turn-on because of the presence of turn-on transients. Under these conditions, the following guidelines apply.

  1. Use an external resistor to parallel the internal Rlimit in the SSR so that the nominal LED current is 2 to 3 times nominal, but no more than the maximum allowable per the device data sheet.

  2. Use an external Rs and Cs to increase the peak current at turn-on to 100 mA (or as much as the specification allows). Rs sets the peak current, while Cs sets the pulse width, usually 1 msec.

  1. Calculating the values of the components for turn on speed-up is straightforward. Using the RDHA702FT10A2FK as an example, the datasheet states that the internal LED diode drop is a nominal 2.6V at a 10 mA drive current. The Rlimit resistor sets this current, and is therefore equal to (5-2.6) V/10 mA, which is 240Ù. The data sheet also states that the maximum allowed LED direct current is 40 mA. In order to add an additional drive current of 30 mA, Rp calculates to be 2.4 V/30 mA, which is 80Ù.

    The maximum peak LED current allowed per the datasheet is 100 mA for 1 msec. In order to add an additional peak current of 60 mA (so that the peak of 60 mA plus the dc level of 40 mA equals the maximum

     

    Surge current limiting with automatic bypassing of a 10 V current limiting resistor and turn on speed-up circuitry.

    of 100 mA), Rs calculates to be 2.4V/60 mA, which is 40Ù. Cs must set this 60 mA peak to have a time constant of no more than 1 msec. Since Cs sees basically just Rs for this time constant, Cs calculates to be 1 msec/40Ù, which is 25 µF. At these higher currents, the LED voltage drop will be higher than the 2.6V used in the above calculations. This means the direct and alternating currents will not quite hit their mark. The designer has a choice here. Either recalculate the values based on actual voltage drop, or leave the values as-is since it will lead to a slightly more conservative design.

    Designing for Survivability in a Radiation Environment

    Any electronic components designated for operation in a radiation environment must be designed for graceful degradation. The idea is to build in enough performance to last through the expected mission lifetime. For SSRs this starts with radiation hardened MOSFETs. For example, the MOSFETs in IR's SSRs can withstand 100 Krad (Si) Total Ionizing Dose (TID) and a Single Event Effect (SEE) of 37 MeV/ (mg/cm2). The PVIs have similar ratings. However, PVIs exposed to radiation suffer some degradation. Some ways to minimize any negative effects on SSR performance include:

    1. Run an LED current of at least 10 mA, and preferably more. Higher LED current increases the degradation capability.

    2. Choose a PVI with two LEDs. This yields more room for degradation.

    3. If possible, choose a slower PVI because they are simpler and therefore more immune to radiation than their faster counterparts.

  1. With the proper design considerations, solid-state relays eliminate the inherent problems with electromechanical relays without creating new ones. For high reliability applications, the result is the improved reliability that electronic components have brought to other consumer, automotive, and industrial electronic products.

     

    A DC SSR, IR’s RDHA710SE10A2QK, used in a solar array battery charger requires a diode to prevent reverse current flow and battery discharge in the off mode.

    Alan Tasker is Engineering lead, Space Products, IR HiRel Products Group. You can reach him at [email protected].

    Web Resources
    For more information on photovoltaic isolators:
    http://rbi.ims.ca/4399-556
    For information on choosing an input resistor for a microelectronic relay:
    http://rbi.ims.ca/4399-557
    For more information on heatsinking semiconductors:
    http://rbi.ims.ca/4399-558
    MOSFETs Make It or Break ItEMR contacts typically have only a few mÙ of resistance and subsequently very low power dissipation. MOSFETs in the SSR can easily have 10 times or greater drain-to-source resistance, or on-resistance. The resulting I2R losses (i.e. heat) must be removed by adequate heatsinking, especially at higher currents. Data and curves on the individual device datasheets aid the engineer in assessing the heatsinking needs for both steady state and transient heating to stay within the MOSFET's safe operating area (SOA) and below the maximum junction temperature.
    For steady state operation, the temperature rise, ÄT, is P x RèJA, where RèJA = RèJC + RèCS + RèSA.
    MOSFET packaging has a direct impact on the RèJC. For example, the typical RèJC value is 18 C/W for a 64-pin flat pack, 0.65 C/W for a 5-pin surface mount, and 1.7 C/W for an 8-pin surface mount. A power dissipation of 5W in the MOSFET in a 64-pin flat pack with RèJC =18 C/W produces a temperature rise of 90C. If the case can be held to 25C, the junction temperature of 115C is safely below the maximum operating temperature of 150C, but the added heat from any transients must be considered as well.

Ink Jet Printer Could Simplify Electronic Circuit Manufacturing

Ink Jet Printer Could Simplify Electronic Circuit Manufacturing

Using a table-top-sized printer, product developers may now be able to build printed circuit boards for devices ranging from cell phone displays to RFID antennae to solar cells.

The new technique, developed by Santa Clara-based Dimatix, Inc, builds circuits a drop at a time by using a piezoelectric print head to dispense liquid silver, nickel, gold or a variety of semiconductor materials onto an electronic substrate. Because it eliminates masking and etching from the traditional electronic manufacturing process and replaces those steps with simple deposition procedure, Dimatix executives say it could enable design engineers to dramatically cut costs on certain projects.

"If every circuit you make is different, or if you have a very complicated circuit that causes masking to be expensive, then this ink jet method is a viable way to build your circuits," notes Martin Schoeppler, vice president of corporate strategic business development for Dimatix. "Here, there is no etching and no 'subtraction' steps."

The key to the new process is Dimatix's creation of the ink jet printer, known as the DMP-2800, which deposits the nano-droplets onto an electronic substrate. The printer also uses a MEMS-based cartridge developed by Dimatix. In the past, ink jet printers could not have been used for such depositions because the heat from a conventional ink jet unit would have destroyed metals or organic materials. Dimatix engineers solved that problem by re-engineering ink jet print heads to use specialized nozzles, pumping chambers and acoustic wave membranes.

Ultimately, the company's executives hope that their new process will be usable in complicated electronics projects that require numerous masking steps, or in situations where construction of prototype printed circuit boards are called for. In both cases, designers could save money by eliminating the need for expensive photomasks.

The company is eyeing a variety of applications, including solar cells, keyboards, light-emitting surfaces, smart cards, ID tags, RFID components, and flexible displays for laptops, cell phones, and handheld games.

"Display companies have publicly announced that they are counting on ink jet technology to replace their current manufacturing methods because it lowers their costs and gives them better precision," Schoeppler says.

Schoeppler says that universities, laboratories, and start-up companies working on application of nano-materials are also potential users of the technology, along with firms that are working toward the Holy Grail of the one-cent RFID tag.

At $30,000 apiece, Schoeppler argues that the DMP-2800 is a bargain when compared to highly complicated masking and etching processes, and is easier to apply. "You fill your cartridge and plug it into your printer," he says. "And you're ready to make an electronic circuit."