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Market Focus: Electrical/Electronics

August 26, 2000

9 Min Read
Market Focus: Electrical/Electronics

One of the fastest-growing markets in electronics is optical media. As outgrowths of the compact disk, DVD and next-generation technology are throwing new curves at molders and resin suppliers, forcing them to tailor their processes and materials to maintain the crucial flatness required and accommodate ever-growing data-storage capacity (see article below).

Henri Luc Martin, director of antipiracy/PCHE for Dow Plastics, states what is on everyone's mind: the CD format will eventually go the way of the 8-Track and Betamax, replaced by much higher-density (up to five times greater data-storage capacity) DVDs and other similar media. To keep in step with this expanding technology, he says Dow's greatest challenge comes straight from molders—material consistency. "One of the largest demands on raw material suppliers for polycarbonate, for instance, is to provide a consistent product that meets all the specifications," he notes, "so that molders can fine-tune their machines, and not have to adjust them continually."

To be efficient, this means optimizing the process from the start, Martin explains. "When CDs first came out, cycle times were probably in the 30-second range, and now they're in the 3-second range," he offers. As with all molded products, shortened cycle time is money in the bank. However, Martin thinks that optimizing operations in the manufacture of DVDs is critical because of the highly integrated nature of the equipment. "You can't afford to have an upset up front," he says. "You lose the efficiency of the whole system."

The most significant impact on molders diving into the new wave of optical media, Martin believes, will be the learning curve. He points out the technological challenge molders will face as the common DVD .6-mm substrate is replaced with a .3-mm substrate in other optical media. "Tolerances for tilt and birefringence are going to be twice as stringent for a higher-density DVD than they are with today's generation of DVDs," he says. "The learning process will be a bit of a challenge, but I think the industry has proven over the last few years that it's achievable."

However, even with the industry's rapid advances, Martin assures us that processing overall will be an extension of current molding practices. Some tooling modifications may be necessary either to accommodate the new resin or to replicate the high level of detail into the disks, but he notes that this is a small component of the overall integrated system. "I would hope that the industry is capable of bringing the polymers and the formats together in a way that minimizes the impact on the molders," he says.

Martin says Dow's biggest challenge in optical media is to develop highly stable products with very low birefringence, low water absorption, better transparency, and high flow to fill thin walls and small pits in the substrate.

Space-saving LCP helps build
strength in thin-wall parts

As electronic components shrink to allow for the manufacture of smaller electronic products, walls get thinner yet must still maintain the necessary strength. Two such applications were molded with Zenite 7130 liquid crystal polymer (LCP) from DuPont, which reportedly provided the dimensional stability and strength required.

The first component is a bobbin that is part of a transformer used in laptop computer modems (see photo, below). Molder United Technical Products (UTP, Fallsington, PA) assisted BG Laboratories Inc. in Binghamton, NY with product development, and then designed and built the bobbin tooling. It also assembles the .14-sq-in-by-.172-inch-high part with termination pins.

Zenite 7130 LCP, a 30 percent glass-reinforced grade, can fill walls as thin as .008 inch, reports DuPont. This maximizes winding space on the bobbin, yet the LCP still provides adequate structural strength and electrical insulation. UTP has been able to hold part tolerances of ±.002 inch, and says that the LCP's heat resistance is similar to that of thermosets (heat deflection temperature is 552F, flammability rating is UL94 V-0).

Another application that uses Zenite LCP is a two-part miniature balun connector for digital transmission lines. The baluns, one-third the diameter of conventional baluns, are used to connect unbalanced 75-ohm coaxial cable with balanced 120-ohm twisted pair cable. "In telecom exchanges and other facilities with thousands of balanced/unbalanced links, the miniature balun can free up precious space needed for additional lines and links," says Steve Manche, a mechanical engineer at AC&E Pty Ltd. of Australia, which developed the baluns.

The part used on the twisted-pair side of the connector is called a stuffer cap (right side of photo, above). Mating the cap to the other side, the base, creates an insulation displacement connection to terminate the wires to metal contacts in the base. The base, which has an integral positioning lug, measures 8 mm in diameter by 15 mm long and weighs .2638g. The cap has a 7.5-mm diameter, is 8 mm long, and weighs .2698g.

AC&E required the assembled parts to be tested for 112 days at 212F to check dimensional stability. While the dimensional changes in high-temperature amorphous nylon were too great to pass this test, those in Zenite LCP were not. In fact, the base-on the coaxial side-had to withstand short-term exposure (approximately 6 seconds) to a temperature of 500F during soldering assembly of small metal terminals. The intricate nature of the components also required a high-flow material. Heliro Pty Ltd. (Warriewood, New South Wales) molded the connectors.

For more information:
DuPont Engineering Polymers
Wilmington, DE
Phone: (800) 441-0575
Fax: (724) 514-9494

Hard drive lever stands up to wear

Just listening to the hum and whir of a computer indicates there's a lot of movement going on inside the CPU. Much of this takes place in the hard drive. The latch lever pictured here is located in the disk drive and is designed to restrict the motion of the drive's suspension arm. This means the material used for the lever must have low outgassing, resistance to wear over thousands of cycles, and must maintain its mechanical properties. Aurum JCR 3030F thermoplastic polyimide from Mitsui Chemicals was chosen because it offers all three characteristics, as well as creep resistance, high strength and modulus, and low coefficient of friction, according to Mitsui.

For more information:
Mitsui Chemicals America Inc., Purchase, NY
Phone: (914) 253-0777; Fax: (914) 253-0790
Web: www.mitsuichemicals.com


More data possible on disks with PCHE

If you think the memory capacity of personal computers has skyrocketed, take a look at optical media. Next-generation technology for molded disks resembling CDs and DVDs is headed toward higher-density media, which means much greater amounts of data can be stored on a single disk. Plasmon, a molder located in the U.K., has produced high-density substrates with the tiny features required to obtain a data density of 15 to 18 GB per layer (see lower image). While no commercial applications are available yet, the success of this trial indicates the possibilities for optical media.

To achieve this level of data density, Plasmon used a polycyclohexylethylene (PCHE) from Dow Plastics. Commenting on the material's performance, Robert Longman, group technical director for Plasmon, says, "These results . . . [demonstrate] the ability of PCHE resin to perform at the faster acceleration and deceleration speeds required for next-generation disk players to read higher information density level."

Good optical purity and clarity in the resin, a 1.51 refractive index, and light transmittance across a full spectrum (as low as 300 nm UV), can enable the industry to move to higher data density standards, say Dow sources. In fact, testing is being conducted to attach two 15-GB disks together, resulting in one 30-GB disk. These increasing capacities, coupled with the high light transmittance of PCHE, mirror advances in laser technology, says Ronald van Slegtenhorst, optical media specialist for Dow. "Next-generation technologies are moving from red lasers to shorter wavelength lasers to focus on the greater number of pits containing more information," he explains.

Because the disks must be absolutely flat, PCHE's inherent moisture level of less than .01 percent was important in preventing warpage. It also precludes the need for drying before processing.

For more information:
Dow Plastics, Midland, MI
Phone: (800) 441-4369
Web: www.dow.com   

Polypropylene spool withstands breakage

Small, delicate computer chips must be protected when stored and shipped. One method of accomplishing this is to attach the chips to a wire and wind it around a spool. Phoenix Custom Molders in Wolfeboro, NH molds such a spool, and found that it needed an especially tough material to pass stringent impact strength tests. "Our customer requires a spool that can withstand a fall to the floor without cracking," says Mark Merrow, plant manager at Phoenix. After experimenting with several materials, the molder solicited recommendations from The Plastics Group for the 8-lb, 27-inch-diameter part. RMC-40 Polifil, a calcium-filled polypropylene, was selected both for its strength and its attractive pricing.

For more information:
The Plastics Group of America, Woonsocket, RI
Phone: (800) 984-4874; Fax: (401) 767-2823
Web: www.plasticsgroup.com

PCT computer connector resists heat

Advances in computer assembly methods have spawned thinner laptops and smaller desktop systems. They have also created a need for materials that can withstand the accompanying temperature increases. An example of an application that involved both elements is a memory connector interface from Thomas & Betts Corp. (Memphis, TN). The connector, which comes in an 80-position version for desktop PCs and a 40-position version for laptops, is used to connect the disk drive and SCSI to the printed circuit motherboard.

The molder, Maloney Plastics (Meadville, PA), had previously encountered fill and outgassing problems with the part. Thermx CG933 PCT, a glass-reinforced, flame-retardant polyester from Eastman, was then selected and proved to be the solution. "Since we switched to CG933, we have been able to shorten cycle times and run production for much longer periods between mold cleanings," adds Randy Hendrich, vp at Maloney.

Eastman's PCT was also chosen because of its low rate of moisture absorption, which resulted in less drying time than materials such as polyamide and polyphthalamide. Resistance to blistering was another factor in Thomas & Betts' decision; Eastman field trials showed none at relative humidities from 0 to 75 percent and at temperatures up to 525F.

Since the material has good flow characteristics, thin sections of the mold fill without flashing, say Eastman sources. Also attractive to the manufacturer was the relatively low cost and a 20 to 30 percent faster cycle time than comparably priced PPS.

For more information:
Eastman Chemical Co.
Kingsport, TN
Phone: (423) 229-6385
Fax: (423) 229-8595
Web: www.eastman.com

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