Design News is part of the Informa Markets Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.


Articles from 2005 In July

Standards Ease Cable Selection

Standards Ease Cable Selection

Designers often don't think about cables until designs are nearing completion, so there's little time to examine the complex specifications. Yet for many harsh applications, cables can have a major impact on reliability and downtime. Lapp USA is attempting to simplify that with a labeling technique based on international standards for factors such as oil resistance and flexibility.

"We're trying to make it easier for an engineer who now has to look at our catalog, which is 800 pages," says John Gavilanes, Lapp's engineering director.

The charts show whether a given cable meets U.S., European, or Canadian standards, as well as international specs. Currently, there are four categories: flame resistance, oil resistance, motion type, and mechanical resistance. Each section has six or more levels, providing information such as standards compliance and life cycles. One benefit is that designers moving into global markets can quickly determine whether they're meeting international requirements, Gavilanes says.

Lapp, which has made cables for nearly half a century, plans to expand by including more standards and categories. "This makes it a lot easier to compare products from different vendors. We think our competitors will look at ways to copy this or improve on it," Gavilanes says. Cable Selection Simplified




Oil Resistance


Oil Resistance

Flame Retardant


Flame Retardant

Motion Type


CF-Continuous Flexing
TCF-Torsion & Continuous Flexing

Mechanical Properties


Mechanical Properties

Seeking the Use of Standard Labeling for Green Parts

Seeking the Use of Standard Labeling for Green Parts

If the parts industry won't create unique part numbers for lead-free parts, how about adopting standards for green labeling? The National Electronics Distribution Association (NEDA) is pushing for parts suppliers to adopt standard messages on labels that indicate a component is lead free. "There are several label standards, one from JEDEC ( and one from IPC (, and those standards address putting a lead-free label on your part," says Barney Martin, VP of industrial practices at NEDA.

Martin notes that the labels are not only important as parts move through the supply chain, but they're also important for those in manufacturing who have to alter production to accommodate differences in the material finishes on the components. "This is an operational issue for people on the plant floor," says Martin. "The label will give the plant folks lots of good information about the composition of the part."NEDA has been pushing hard for suppliers to adopt unique part numbering for lead-free components. The association released a position paper last year on the conversion to RoHS compliant components on behalf of its distributor members ( The central point of the paper was a call for suppliers to adopt unique part numbers for lead-free components. The group believes the absence of unique part numbers will cause supply chain difficulties.Yet NEDA executives concede that not all suppliers will issue unique part numbers. "We believe there ought to be a part number change, but some folks are not making that change, so the next issue is labeling," says Martin. "People are already delivering their parts RoHS-compliant and they're using all manners of labeling to communicate they're lead-free. We want the industry to standardize on labeling."Martin notes that other RoHS issues came up during the association's one-day conference on the subject. The meeting was held in Chicago last June. "There are problems with the way companies communicate that their parts are lead free," says Martin. To help alleviate the chaos that comes as each supplier communicates its lead-free status in its own manner, NEDA has produced a spreadsheet suppliers can use to standardize their communication to their customers. It's available for download at no charge: also notes there is continuing confusion over the manner in which suppliers deliver information on the material content of their components. "The industry still needs to address the issue of chemical content reporting," says Martin. "Suppliers are giving that information in different formats." He notes that iNEMI has issued a standard on the communication of chemical content that may become the industry standard.

Big Companies Better Prepared for RoHS

Big Companies Better Prepared for RoHS

Major manufacturers and distributors in the electronics industry are well prepared to meet the requirements of the European Union's RoHS and WEEE directives. But many of the small- to medium-size component suppliers are falling short in getting up to compliance. "Across the board large companies are more prepared than small companies. The large companies are prepared, so they don't have to act immediately," says Eric Karofsky, senior analyst at AMR Research. "The large companies always understand risk better. They have better planning capabilities and more capacity to spend time assessing risk."

He notes that large companies view regulations as risk factors and they have a institutional capacity to assess risk and plan mitigation strategies well in advance of regulation deadlines. Not so with small companies. "Companies like Motorola and HP are well under way in understanding what is necessary to comply," says Karofsky. "Most of the small- to medium-size businesses are behind the times." The large companies, however, depend on components from small- and medium-size suppliers. So the major companies have started to lean hard on their suppliers to get up to compliance. "Initially, the small- to medium-size businesses hampered the large companies' ability to comply, but the large companies have the power," says Karofsky. "A small component supplier may not be able to supply the component materials information. That provides a momentary exposure problem for the large manufacturer, but long term, the small component supplier will need to get up to speed or lose market share." Karofsky views RoHS compliance as a major competitive factor among small- to medium-size component producers. Not only must they produce lead-free versions of their components, they also have to manage the material content records to back up their claims of compliance. Those companies that can manage the transition best will gain marketshare over those suppliers that fall down on compliance and materials declaration. "If small companies continue to be a problem, the large companies will penalize them. If the supply base is compliant, that sets a baseline for enforcing compliance," says Karofsky. "Eventually, competition will rule and the small supplier will get up to compliance to get more business. That's already starting to happen."

For Automakers, it’s Bandwidth, Bandwidth, Bandwidth

Pipe flow: It’s a hydraulics term, only remotely associated with the likes of microprocessors and software. But over the next ten years, “pipe flow” is going to be transformed into an electronics term, as automakers face a computing dilemma that will dwarf anything in the history of the desktop world.

Their challenge, in essence, is to push tens of millions of bits of data per second down an electronic pipe, allowing scores of microprocessors to “talk” to each other, enabling flawless operation of brakes, throttles, radios, CD players, door locks, window lifts, engines, transmissions, seat motors, heaters, air conditioners, windshield wipers, airbags, cell phones, steering wheels, and countless other items, so that not one life is ever lost because a data packet got hung up somewhere, causing the brakes to fail. To accomplish that, automakers are going to need a big electronic data pipe, bigger than the 1 Mbit/sec offered by today’s CAN (controller area network) buses, and maybe even bigger than the 20 Mbits/sec of the industry’s emerging FlexRay bus. In essence, they’ll need a fat pipe capable of gulping down millions – maybe billions – of bits of data per second and spitting those bits back out to the proper locales. No one knows for sure, but a few forward-thinking engineers believe that the industry would do well to start considering bandwidths in excess of 100 Mbits/sec, now. “For the short term, we still see CAN as the major automotive bus,” says Hans De Regt, marketing director for Philips Semiconductors’ Automotive Business Line. “But over the long term, we’re going to need something with a lot more bandwidth.” Indeed, the computing necessities are almost mind-boggling, not only because of the sheer volume of data, but because of the requirement that the microprocessors talk to one another. Ultimately, engineers foresee a day when the forward-looking radar sensors will talk to the brakes and airbags, when cell phones will communicate with radios, and when the rain-sensing wipers will talk to antilock brake modules. Doing that, of course, requires a more centralized system. It will no longer be sufficient to discretely control a single system with its own dedicated, isolated microcontroller. “We want to look at the entire vehicle, from end to end, as one big system,” notes Pat Jordan, director of systems engineering for Motorola Corp.’s Global Software Group. “And today’s bus architectures are inadequate for doing that.”

Distant future: Motorola’s switch fabric, a mesh of interconnected nodes, could boost bandwidth one-hundred-fold and enable engineers to wire the vehicle, end-to-end, as a single system.

Beyond buses

Predictably, there is disagreement over how to do it, or even whether it needs to be done at all. But in some quarters, a sense of urgency is growing. The auto industry, after all, typically works five years ahead, and with each successive year, electronic systems are growing maddeningly more complex. That’s why most automotive engineers have begun pushing hard in an effort to settle on a technology, improve it, and standardize it. 

Until this year, a growing number of automakers had been migrating toward FlexRay as a potential solution to some of those growing complexity-related issues. FlexRay, after all, offers bandwidths approximately 10 times greater than those of the CAN bus. Late last year, however, Motorola Corp. introduced an alternate concept. Switch fabric, a technology that has made its name in telecommunications switches and relays, could have potential as an automotive network because it offers bandwidths 100 -- and possibly even 1,000 -- times greater than those of CAN, the company says.  “We looked at the Internet and asked, ‘How can we bring those features of the Internet into the communications architecture of a vehicle?’” Jordan says. “And we saw switch fabric as the best way to do that.” In essence, Motorola’s switch fabric is not a databus. Rather, it is a mesh of interconnected nodes, in which any single node can “talk” directly to any other node by navigating a direct path across the wire mesh. The concept, however, is not co-opted directly from the Internet world. Instead, the computing giant has devised an automotive-centric “distributed switch fabric” concept, employing a limited number of nodes that operate like small packet data switches. This is accomplished primarily through software protocols, and by combining those protocols with the physical layers of other databuses, such as CAN or FlexRay.


Five to ten years out: Automakers plan to use CAN buses (depicted in blue) for powertrain, LIN (green) for simple motor actuation, Safe-By-Wire (red) for airbags, and time-triggered FlexRay (yellow) for safety critical applications. (Figure courtesy of Philips Semiconductors)

The resulting level of speed is magnitudes ahead of anything available with existing databuses, such as CAN, J-1850, LIN, ByteFlight, or even FlexRay. Used with a CAN physical layer, for example, Motorola’s distributed switch fabric can provide bandwidths of 1 Mbit/sec at each link, with as many as 256 links, resulting in an ultimate theoretical bandwidth of 256 Mbits/sec. Combining a FlexRay physical layer with the switch fabric protocol, the bandwidth soars even higher – to about 10 Mbits per link. With 200 links in the mesh, the result would be an ultimate bandwidth approaching 2 Gbits/sec.   “All of the communications in a switch fabric are point to point, so all the links can communicate simultaneously,” notes Jordan of Motorola. “Obviously, you can never utilize 100% of that, but that’s true of any architecture. The point is, you get a lot more bandwidth with switch fabric than you do with CAN or any databus.”

No more ‘baby steps’

Ultimately, the bandwidth available from Motorola’s switch fabric architecture is almost limitless. In the telecommunications world, where switch fabrics are rapidly nearing acceptance, engineers are talking about bandwidths of 2 terabits/sec. No one has as yet dared associate such numbers with the auto industry, but Motorola engineers have acknowledged that their switch fabric protocol could offer speed gains of 1,000 times over CAN, which is today’s most commonly used automotive bus structure.

Motorola engineers stress that their switch fabric concept is different because it is not a bus architecture. “With any bus architecture, modules on the bus have to have equal access,” Jordan says. “Therefore, at some point in time, you’re bound to run into a bandwidth issue.” Jordan argues that bus-type networks must always be sub-divided into multiple buses and gateways. Hence, he says, they foster an atmosphere in which a microcontroller must be added to accommodate every new feature. In contrast, the faster communications abilities of the switch fabric would enable engineers to eliminate the “one processor-per-feature” mentality. Experts say that automotive engineers find the concept compelling, but are viewing it as a very long range solution. “It’s a good way for the auto industry to deal with the bandwidth issues surrounding CAN,” says Paul Hansen, publisher of The Hansen Report on Automotive Electronics ( “But it’s something you won’t see for at least 10 or 15 years, if that.” Many automotive engineers also argue that CAN has stood the test of time during roughly two decades of automotive development, and that any new network will need to prove itself in similar fashion. “When you bring any new network into a vehicle, you’ve got EMC (electromagnetic compatibility) issues to deal with, especially at higher bandwidths,” notes Scott Monroe, systems architect for Texas Instruments’ Mixed Signal Automotive Business Unit. “It still comes down to the fact that you’re trying to transmit data at a high rate, and you’re trying not to give off any electromagnetic emissions from the copper wire as it goes through the car.” Motorola engineers, however, believe that the time is right to look at switch fabric, especially as more automakers recognize that CAN may be running out of horsepower. “At this point, instead of taking baby steps, it might be time to look at the possibility of making a bigger change,” Jordan says.

Shorter term solution

Such dramatic changes, however, are unlikely to be made before FlexRay makes its way into vehicles. FlexRay, originally developed as a bus for so-called “by-wire” automotive applications, was originally seen as a method for providing reliable operation for safety-critical systems. In particular, it was aimed at steer-by-wire and brake-by-wire systems, among others, because it offers high bandwidth and, in particular, fault tolerance. It has the backing of most of the world’s biggest automakers, including General Motors, Ford, DaimlerChrysler, and BMW.

FlexRay is considered a strong candidate for such safety-critical applications because it incorporates a time-triggered software architecture (rather than event-driven), which ensures that there is always a slot for important messages. As a result, it provides a level of redundancy for steering, brakes, and other systems that will no longer have the inherent redundancy of hydraulics. More recently, however, automotive engineers have begun to look to FlexRay to play a larger role in the vehicle. As a central backbone, they say, FlexRay could solve the bandwidth issues that are fast approaching as CAN nears its limit. Some engineers within General Motors and elsewhere want to use FlexRay to control powertrain, chassis, and airbags, as well as drive-by-wire systems. Once again, bandwidth is a key to such thinking: While CAN offers a data rate of less than 1 Mbit/sec, FlexRay’s two-channel configuration offers 10 Mbit/sec per channel, for a total of 20 Mbit/sec.  Semiconductor makers say they have already started to develop chips for FlexRay and are selling them to automakers and tier-one suppliers. Texas Instruments, for example, says that it has “customer commitments” for its TMS470 platform of automotive microcontrollers.

The TMS470 controllers, based on the 16/32-bit ARM 7 core architecture, are expected to see use in advanced chassis, airbag and body control systems. Philips Semiconductors and Freescale Semiconductor, meanwhile, announced earlier this year that they have agreed to share their FlexRay technologies for use in powertrain and advanced body applications.

Ultimately, both companies say they are targeting brake-by-wire, steer-by-wire, and active chassis management.

Electronics engineers from all the companies stress, however, that CAN buses will continue to play a dominant role in electrical architectures for years to come. CAN technology, they say, is the product of tens of thousands of man-years, and automakers aren’t about to abandon it soon. “In ten years, CAN will still be the predominant bus in the majority of vehicles,” notes Monroe of Texas Instruments. “The industry has too much of an entrenched infrastructure to drop it quickly.” Most engineers believe that the auto industry will slowly change its electrical architectures, most likely by employing a mix of protocols. FlexRay, they say, could eventually serve in body and chassis applications, LIN (local interconnect network) in lower-bandwidth applications such as door locks and window motors, Safe-By-Wire in airbags and other safety devices, and CAN may still hold its ground in powertrain. 
Ultimately, however, they expect the number of nodes and the number of microcontrollers to decrease. Otherwise, they argue, system complexity could spiral out of control.  “In ten years, we expect to see big super-nodes, with FlexRay for the high-bandwidth applications and LIN for sensing and actuating,” notes De Regt of Philips Semiconductors. “The goal is to make a smaller number of nodes and combine more applications into single nodes.” Either way, most automotive engineers know they’re going to need a bigger “data pipe.” As they move toward forward-looking applications such as adaptive cruise control, collision avoidance, and automated lane-keeping, communication signals within the vehicle could increase by ten-fold. Under such conditions, the concept of a central electrical backbone – one that’s not divided into sub-buses and gateways – will grow in importance. “There’s no way you could trust an entire vehicle to one of today’s conventional buses,” concludes Jordan of Motorola. “With today’s buses, bandwidth is always going to limit you.”






Less than 1 Mbit/sec  

Powertrain, chassis, instrumentation

Available now


10-20 Mbit/sec  

Drive-by-wire, body, powertrain 

5-10 years out

Switch fabric  

Into the gigabit range  

Central vehicle backbone  

15-20 years out

For more information on…

Motorola switch fabric, go to, and request information on automotive switch fabric.

FlexRay, go to

CAN buses, go to

M/V Lollipop, Now With Diesel Electric

M/V Lollipop, Now With Diesel Electric

Siemens has been outfitting big naval and commercial vessels with diesel electric power for years. Its yacht systems arm only recently began addressing the sub-megawatt market, the recreational end populated by many, many smaller vessels such as the April K, a 48-foot cruiser out of St. Pete Beach, FL.

The reason for the delay was mainly technological, according to product manager, Thomas Orberger. The company had to wait for semiconductors to achieve sufficient power density to make an inverter small enough and powerful enough to fit in a pleasure craft. Now that it's here, the system promises boat owners better fuel use, more maneuverability in close quarters, and greater space on board. Paul Smith, owner of the April K, says she's much quieter from the bridge, too.

Smith replaced his vessel's two Caterpillar V-8s with a single 210 hp Cummins diesel, which now couples to the Siemens generator. Electricity produced there runs through a Siemens inverter, then to a pair of variable speed drives which power the twin synchronous ac motors and screws.

April K owner Smith stands in an almost-empty engine bay. It was once chock full with twin Cats.

According to Orberger, the inverter acts as a rectifier too, rectifying all ac inputs-from the main generator, the auxiliary generator, or shore power-to create a common grid. The electricity is then dispatched in the form needed: single phase ac for the hotel loads, three phase ac for propulsion, and dc for the batteries. According to Smith, he could maneuver the boat at the dock on shore power alone. With the room he gained by losing one engine, Smith added stabilizers, a water purifier, a freezer, and a washer/dryer. He's also been able to go to bigger props with "noticeable" increases in pitch, because he now has "fully customizable torque to the propeller."

From the bridge, Smith can monitor engine performance while keeping track of operating history.

The single diesel, together with a smaller auxiliary generator, lets the yacht dispense with a second main engine, dispelling an argument that boaters have hashed over for years: whether two engines are better than one. With direct drive engines, a second power plant added reserve capacity to get the boat home. With the Siemens system, a boat with a disabled main engine can still return to port on the auxiliary generator. And the reverse is true, Smith adds: "I can run my air conditioner off the main engine."The commercial system was first used in diesel-electric buses, Orberger says. "We've moved it from there into marine system and cranes," he says. The system offers completely integrated power management which communicates via SAE CANbus protocol to an HMI on the bridge. There, Smith can display engine rpm, temp, torque, hours, and so on, almost like a commercial vessel. Safety remains paramount. If the computer malfunctions, hard wiring of the inverter gives Smith "get-home capability."

Molding Multiphysics

Molding Multiphysics

Structural analyis codes already do a good job predicting the performance of molded plastic parts. Yet, their results never tell the full story because the mechanical properties of those parts depend so heavily on the molding process. That's why plastics-savvy engineers often supplement their structural analysis work with mold filling simulations that can reveal the influence of the molding conditions.

In the past, engineers had to do quite a bit of importing, exporting, and tweaking of meshes and models to synthesize the results of these two different types of simulations. And juggling all those results took time. "Some analyses that made sense in theory just weren't practical to run," notes Paul VanHuffel, a senior engineer and simulation expert at Cascade Engineering, a large injection molding firm that recently launched a CAE consulting service.

Now, Moldflow Corp. has redefined what is and what isn't practical. Taking a multiphysics approach, the company has fully coupled its filling simulations with its own 3D structural analysis code. While it doesn't replace dedicated structural analysis products, this multiphysics capabilility has helped Moldflow's power users learn new things not only about their part performance but also about the economics of their molding processes. "Multiphysics has opened up new realms of analysis for us," says Van Huffel.

Moving Metal

The most important of these new realms involves performing a structural analysis of the the mold and molding machine components during the filling and packing phases of the injection molding cycle. Simulation codes--and maybe a few engineers--have long assumed that the mold and machine elements remain rigid during the high-pressure onslaught of the injected plastics. But that's just not so in the real world. "Any engineer who has spent time around a molding shop knows that the metal moves," says VanHuffel.

According to VanHuffel, understanding how the mold and machine deflect provides valuable insight into a part's performance attributes, including weight and shape. It also can provide information useful in tool design. And it can help determine the best size molding machine for a job, a decision that will affect piece part costs.

Moldflow offers its structural analysis capabilities as part of the "Core Shift" module found in its Version 5.0 software. As its name suggests, this module began as a way to simulate the deflection of mold cores subjected to the pressure of the plastic melt flow. The software works by taking the pressure distribution results from the filling analysis and plugging them into a structural analysis to calculates core deflection. "The pressure distribution of the melt on the core becomes a boundary condition for the structural analysis," explains Moldflow product manager Murali Annareddy.

The software then uses this deflection result to adjust the thickness of those mesh elements that represent the melt flow around the core--so that subsequent time steps in the filling analysis reflect any changes in core position. This iterative process repeats throughout the filling and packing cycles at user-defined time steps, providing a quasi-dynamic view of how deflecting cores can influence filling as their movement changes the shape of the cavity.

And the module doesn't stop with deflection of the cores. The same multi-physics approach can also look at the deflection of any mold feature--including slides, ejector systems, and even the mold plates. It can also be used to analyze the movement of inserts inside the tool. Over the past year, Moldflow users have analyzed core shift in wide variety of applications. These include cases where the tooling has delicate features, such as the molds for electrical connectors. They also include applications whose molds have long, unsupported cores--from syringes up to industrial trash containers.

Beyond Core Shift

VanHuffel has taken Core Shift even further. He's devised a way for to predict both the stretch of the tiebars on the molding machine's clamp end as well as an injection mold's tendency to flash.

Tiebar stretch is a normal part of a molding machine's clamp operations, but it can becomes excessive when molders try to run molds on the smallest feasible molding machine in an effort to keep hourly production costs in check. In these "over-tonnage" situations, the tiebars can stretch enough for the mold to open slightly. In the worst cases, the mold will flash as plastic leaks through the open parting line, driving up rejects or triggering costly flash removal operations.

Even if no flash occurs, VanHuffel has found that parts gain weight since they slightly open tool holds more plastic. On big parts, that extra material adds up. "Smaller presses might seem to save money, but not if parts end up heavier than they should be," he says. "On smaller parts, the extra material may not matter as much from a cost standpoint," he continues. "But you run a bigger risk of tool damage since flash can erode the parting line."

In the past, VanHuffel managed to simulate this over-tonnage behavior "manually" by combining the Moldflow simulation with calculations made in an Excel spreadsheet. Aside from taking too much time, this method had accuracy limitations because it assumed the tool was rigid. It thus neglected the deflection of the tool steel and the stiffness enhancements from the mold's support components. Both of these factors tend to offset the influence of tiebar stretch, VanHuffel notes.

With Core Shift, VanHuffel now meshes the entire core-side of the mold along with the tiebars and most other parts of the molding machine's clamp end. He also adds a series of vanishingly thin (1E-6) flow elements along the parting line of the tool. These "flash" elements approximate a zero-thickness element, something that the Moldflow code doesn't currently support.

When the multiphysics analysis runs, VanHuffel "stretches" the tiebars with a displacement load corresponds to the clamp force required for a given molding job. If that load stretches the tiebars enough to open the tool, it shows up in the coupled filling analysis: The thin "flash" elements get thick enough to allow plastics to flow into them, indicating that the tool would flash. Conversely, if the mold closing forces can overcome the tiebar stretch, the flash elements will, in effect, remain at zero.

So far, the results of the analysis have been dead on. "We've been able to predict deflection within 0.001 inch of the deflection measured on actual parts," Van Huffel reports.

And he say that Moldflow's multiphysics capabilities do more than predict flash. To take one example, similar techniques can also help balance runner systems in large parts with many drops--since unbalanced conditions can exert unequal forces on the tiebars. He has also applied his flash elements method to predictions of whether mold vents will clog.

As the multiphysics capability evolves, VanHuffel believes he'll be able to do even more with the software. His next project could be the most valuable one yet. Once Moldflow adds the ability to display not only deflection but also stress distributions--a feature that's currently in the works--VanHuffel says he'll actually be able to predict fatigue life of tooling components. "That will be a huge development," he says.

Cascade Engineering has used Moldflows multiphysics capabilities to analyze tooling and machine deflection during the injection molding process. The analysis approach has been particularly helpful with large parts, such as this garbage cans.

Web Resources

In addition to its injection molding business, Cascade Engineering has launched a consulting service that will run mold-filling and structural analyses. For more information, visit

For more information on Moldflow, go to A white-paper on Over-tonnage Prediction using Moldflow can be found at

RoHS Summer School

RoHS Summer School

Engineers will get a chance to go back to school this summer to learn about RoHS and its impact on the products they design. IPC – the Association Connecting Electronics Industries – has lined up a series of weekly Webcasts, called RoHS Summer School, to teach the basics of the industry’s move to lead-free parts.


The series began on July 14 and runs every Thursday morning for an hour beginning at 8:00 EDT. The final class will be on August 18. The cost for IPC members is $450 for the entire series ($750 for non-members) or $100 for each class ($150 for non-members). Presenters come from suppliers and industry groups.

Here’s the schedule:

July 14 – Introduction to RoHS

July 21 – How to comply with RoHS

July 28 – Standards activity IPC-1752

August 4 – Implementing materials declaration

August 11 – Test methods for determining RoHS substances in electronics

August 18 – Implementing electronic materials data exchange

Adhesives may replace solder

Adhesives may replace solder

Georgia Tech is testing conductive adhesives as a potential alternative to tin-lead solder. Electronics Weekly reports that Georgia Tech professor C.P. Wong who is working on adhesive technology believes the Georgia Tech team is making progress on improving the properties of conductive adhesives.

Conductive adhesive consists of glue filled with metal powder. One technology Wong is working on involves self-assembling molecular conductors that provide a direct connection through the adhesive. Wong admits that the adhesives by themselves do not measure up to metallic solders, but he notes that when the adhesive is incorporated in self-assembled mono-layers the electrical conductivity and current-carrying capability compares well with traditional solder joints.

Another issue Wong is working on is the decreasing performance of adhesives when exposed to high humidity over an extended period of time. He blames oxidation for the decreased performance. He is currently testing materials such as acid that may inhibit the oxidation.

This Fishing Reel Features Action

This Fishing Reel Features Action

Looking for better performance and lighter weight without sacrificing strength? Consider magnesium injection molding, which combines the best of plastic injection molding with die casting. One example is a prize-winning center housing of a hot new fishing reel.

Once avoided as an unpredictable process, magnesium molding showed its merits on the reel frame produced by Phillips Plastics for Marsh Technologies, Inc. (St. Charles, MO). The one-piece magnesium frame offers better rigidity than bolted metal frames sometimes used in bait casting. A new product, the mag frame replaced plastic or aluminum used in previous designs. Weighing 31 grams, the reel offered lighter weight compared to aluminum and provided part density and surface quality that could not be achieved with a plastic molding. It won one of the top awards in the 2005 International Die Casting Competition held by the North American Die Casting Association. Judges noted that the magnesium molding process could create complex geometry with varying wall thickness, while maintaining tight tolerances of bores and surfaces for mating components. The complex geometry, including undercuts, was made possible through three hydraulically actuated slides included in tooling design and produced on a tight production schedule. Good venting on a mag tool requires engineering that is as much art as science. Production of the parts takes place in specially made injection molding machines, starting with the melting of magnesium chips. Magnesium molded parts are cooled at lower temperatures (by 50-100F) than plastics. The process yields net shape parts, although post-machining is typical. The smallest part size achieved in the Phillips shop is 21 grams versus the common industry standard minimum shot size of 65 grams. Maximum part weight is 1816 grams in an 850 metric ton press. The bigger parts are aimed at electronic enclosure or automotive applications. "Our forte is precision molding with tight tolerances, good surface finish and action in the tool," comments Dave Coon, senior project engineer at Phillips Plastics, Menomonie, WI. Phillips commits to NADCA precision tolerances in its molding processes, which recently re-located to a dedicated facility.

Mag Molding or Die Casting?

Mag Molding or Die Casting?

Injection molding of magnesium permitted a new design for a revolutionary miniature bar code scanner and provided additional benefits in protecting sensitive internal electronic components from water and other potential environmental problems.

The MS3 scanner from Microscan Systems "may not be smallest scanner available, but it is the best combination of size and performance," says Malinda Elien, staff mechanical engineer for Microscan, Renton, WA. "This is the most compact, high-performance mechanical design around." The chassis had to hold tolerances of plus or minus 0.002" in very thin wall sections (0.027"). Molten magnesium can travel longer distances prior to solidification than is possible with conventional die casting. The high pressure of injection molding and careful tool design made the difference. The density of the magnesium molding process (called thixomolding) was also a critical difference. "We were able to achieve thinner wall sections without having to worry about water leaking through random pores in the metal," said Elien, who had the final call on whether to try thixomolding or stay with die casting. "Initially we were trying to decide between Phillips Plastics and our traditional die-casting vendor," Elien said. "We never had the question in our mind if Phillips was telling us the truth or if they were telling us what we wanted to hear...Every day I am happy that I made the decision that I did."