Material Innovations
November 2002
NASCAR opts for Cymat material
 Cymat's aluminum foam material is used on either side of the reduced-size fuel cell to keep it in place. |
As part of an ongoing commitment to increasing driver safety, NASCAR has mandated the use of smaller fuel cells for its super-speedway races. The smaller fuel cell must be located and constrained within the existing well in the trunk of the car. Cymat's proprietary SmartMetal aluminum foam was chosen for the application.
SmartMetal has a high strength-to-weight ratio, good energy absorption characteristics, and good thermal and sound insulation properties. It increases driver safety by acting as an energy absorber in the event of a collision in addition to constraining the fuel cell within the trunk well, according to Cymat. Two blocks of Cymat SmartMetal are installed on either side of the fuel cell.
Cymat's involvement with NASCAR began shortly after a fatal accident involving driver Dale Earnhardt. That crash, in the season-opening race at the Daytona superspeedway in 2001, was the impetus for a safey initiative at NASCAR. The company has been working with engineers at the NASCAR Technical Center since that time on a number of initiatives.
Fifty teams outfitted two cars each with Cymat SmartMetal for an super-speedway race in October.
"These projects provide a high visibility testing ground for our revolutionary Cymat SmartMetal technology," said Michael Liik, Cymat Chairman and CEO. "Many of the advanced technologies that we take for granted in today's cars were originally tested and proven in racing venues before they were adopted in mainstream production cars."
The proprietary, versatile process to produce Cymat SmartMetal combines alloyed aluminum with a metal matrix composite to create strong, lightweight panels and shapes or to fill cavities. Processing is relatively low-cost, according to the company. Cymat's principal focus is on automotive, where aluminum foam is ideally suited to the industry's objectives to make vehicles lighter, safer and better for the environment.
- Patrick Ponticel
LNP's Verton MFX for Mazda modules
 The front-end (top) and door modules from Mazda are made of a low-viscosity, high-flow Verton MFX polypropylene composite. The front-end modules are the first in North America to be made of long-glass-fiber-reinforced thermoplastic.  |
In what LNP Engineering Plastics Inc. describes as a North American first, Mazda Motor Corp. has introduced front-end and door modules made of long-glass-fiber-reinforced polypropylene. The high-strength material, a Verton MFX polypropylene composite licensed by Mazda, is being supplied by LNP.
The so-constituted modules on the new midsize Mazda6 are strong, light, and highly recyclable, according to LNP. They combine parts, integrate functions, and provide body structure support. The front-end module holds radiator components, fan assembly, and hood latch. The door module holds speakers, latch assembly, door lock actuator, and glass window regulator.
Unlike earlier modules made from steel stamped parts or glass-mat-reinforced thermoplastics processed by press molding, the new ones are made from low-viscosity, high-flow composite with a highly crystalline structure that can be injection-compression-molded or injection-molded. As such, they can be molded to thinner wall sections, and are much stronger, says LNP.
"Mazda's engineers, in partnership with LNP, developed the new material and the injection molding technique for the large parts," explained Matt Miklos, Global Verton Business Leader for LNP. "As a result, the glass fibers are significantly longer after molding than with conventional injection molding. The longer glass fiber length means higher impact strength." In addition, LNP notes, the process results in low molded-in stress for good dimensional control.
The very low viscosity of Veron MFX increases flow by more than 30% compared with conventional long-glass-fiber-reinforced polypropylene. The result is a resin-rich, higher-quality surface. The Verton MFX composite used in the Mazda application also provides improved high-temperature fatigue resistence compared to similar composites based on nylon, LNP says.
- Patrick Ponticel
Marelli chooses DuPont ceramic materials for fuel injection
 This multilayer circuit for a Fiat fuel-injection system uses DuPont QM42 dielectric. |
Magneti Marelli Powertrain was faced with a choice of using either low-temperature co-fired ceramic or thick-film multilayer technology for the design of an advanced fuel-injection system for the new Fiat Punto. In the end, the company decided to use a DuPont ceramic material.
The fuel-injection module, designed in-house, is located under the car bonnet and equips the Fiat Punto eight-valve, Fiat Panda, Lancia Y, and other models. The circuit of the injection module consists of a ceramic substrate measuring 9.5 x 3.3 cm (3.7 x 1.25 in), with a thickness of 0.635 mm (0.025 in). The power and control sections of the module are incorporated on the same alumina substrate. This complicated multilayer circuit interconnects a sophisticated microprocessor, other IC chips (including power devices), and more than 200 passive components, resistors, and capacitors.
The power section has three devices soldered onto heat spreaders that are glued directly to the ceramic substrate. The passive components, mostly of 0603 size, are also epoxy-attached to the circuit. The size of the circuit is such that a master 4 x 4 in (102 x 102 mm) alumina substrate will accommodate a total of three injection modules.
The circuit is built using DuPont QM21 PdAg and QM14 Ag conductors for the power section, the power devices being connected to the control circuit using heavy Al wire. In addition to PdAg and Ag conductors, the control circuit section also uses 5771 Au conductor, QM-type via fill conductors, and QM42 dielectric. The control section is therefore complex, requiring three interconnect layers, with gold bond pads printed over the last dielectric layer. Each dielectric step involves the printing, drying, and firing of two or three separate dielectric layers. The total number of firings is about 10.
An important element of the multilayer system chosen by Magneti Marelli M Powertrain for the injection module is DuPont QM42. This very robust dielectric combines optimum electrical and mechanical properties that eliminate the risk of electrochemical reactions and keep circuit bowing under control, thus providing the necessary planarity for the bond pads.
The "brain" of the condensed circuit is a semicustom microprocessor with more than 100 I/O bonds with a "fan-out" on two staggered rows. The total number of bonds, including 30 and 50 µm (1180 and 1970 µin) gold wire bonds, is more than 200. Al wire is used for the many bonds of the power devices and for the outgoing connections. The circuit is mounted on an aluminium heat sink and placed in a plastic casing, which is tall enough to protect the wire bonds and the outgoing connections.
According to Magneti Marelli Powertrain's circuit designers, the biggest challenge in fabricating the injection circuit was to make sure that the bond pads for the microprocessor were printed on a well planarised top dielectric layer, hence the importance of QM42.
- Patrick Ponticel
