By John Rhea
WASHINGTON - Semiconductor manufacturers are expressing doubts about the new "Class-T" category of low-cost electronic devices for commercial spacecraft, which is in the final stages of preparation at the Defense Supply Center Columbus (DSCC) in Columbus, Ohio.
The new semiconductor classification is due for presentation next month at a meeting of the Joint Electron Devices Engineering Committee (JEDEC) in Columbus, Ohio.
At issue is the desire among commercial spacecraft systems designers to increase their use of commercial off-the-shelf (COTS) parts.
Commercial space OEMs are looking to COTS not only to cut costs and get their satellites into orbit quickly, but also to retain confidence in the reliability of the COTS parts.
Historically, reliability guidelines are spelled out in the Defense Department`s Qualified Parts List (QPL) and, since the introduction of performance as the principal criterion, the Qualified Manufacturers List (QML). Since DOD and NASA designers would likely use the new class of parts sparingly if at all in their programs, the semiconductor makers question why a new classification should be created for only a small group of users.
Addition to QML
Class-T would be an addition to the three existing classes on DSCC`s MIL-PRF-38535 QML for parts approved for use in military and space programs. It would embody less rigorous performance specifications than the top-of-the-line Class-V, required for critical space applications (including radiation hardening and radiation tolerance). It also would be less rigorous than Class-Q, used for most military programs. Yet Class-T would be more demanding than the bottom-of-the-line Class-N, which essentially consists of plastic parts and represents only a few dozen part types.
Leading the drive for a new QML class tailored to the cost- sensitive commercial space industry have been officials of Hughes Space & Communications in El Segundo, Calif., and other OEMs for the past two years.
This drive culminated at a JEDEC meeting in Orlando, Fla., in May. At that meeting, participants agreed to circulate the idea among potential government users - notably those at the U.S. Air Force Space Systems Division in El Segundo, Calif., and at the NASA Goddard Space Flight Center in Greenbelt, Md. - the space agency`s lead field center for electronic component issues. Leaders at those two organizations had opposed the idea of Class-T in the past, and DSCC officials last month were incorporating their responses in a final draft to be unveiled next month.
NASA officials still oppose the idea. George Kramer, chief parts engineer at Goddard, bases his opposition on the vagueness of Class-T: "vaguely defined in the sense that the process flow is left up to the supplier and can vary from vendor to vendor or lot to lot.
"Considering this vagueness," he adds, "we strongly objected to the statement in the original draft that somehow `this class is intended for satellite and similar operations`," although DSCC has since dropped that language. "We remain concerned that if this cost-driven classification becomes attractive to OEMs involved in high-volume satellite builds, which accept higher risks, then ultimately these parts will trickle into NASA builds," Kramer concludes.
September meetings
As matters now stand, the JEDEC will receive the draft Sept. 23 from a DSCC team including Michael Adams, team chief, and his associate, Monica Poelking. Adams outlined the QML program at COTScon`98 in May, and Poelking has been coordinating the responses.
On Sept. 22 a task group headed by Mark Porter of Boeing Aerospace, Seattle, is due to present the results of its study, known as Design Guidelines for Spacecraft Parts, which represents the users` views on how designers could implement COTS parts in future commercial space projects. The JEDEC meets about three times a year.
Where the issue gets sticky is the virtually universal apathy of the parts makers. Experts at UTMC Microelectronic Systems in Colorado Springs, Colo., are taking a "wait-and-see" attitude, says Myles Standish, military product assurance engineer.
Meanwhile, Joe Benedetto, UTMC`s principal reliability engineer, points out his company is already "meeting the spirit of QML" by optimizing the flows of its Class-Q and V parts to reduce non-value-added steps and therefore try to meet the OEMs at least half way on the price issue. "We feel we`ve done that," he says. "Where does a T flow fit in?"
John Hartman, defense business development manager at Analog Devices of Wilmington, Mass. - and an outspoken critic of any efforts to relax parts specifications - questions the wisdom of trying to achieve savings on the electronic components when they represent only a few percent of the total cost of a commercial space project. Electronic components, he estimates, represent 30-40 percent of space mission success.
At the Analog Devices West Coast operations in Santa Clara, Calif., Victor Patel, product line manager, says he wants to work with the OEMs but insists that the most important issue is wafer fab, not test. "We should be building in reliability, not testing in reliability," he says. By reducing some of the extra tests required for the V level, Analog Devices could cut costs by 45 percent on 1,000-piece orders and 55 percent on 10,000 pieces, he says.
T. S. "Stoney" Edwards, managing director of the government technology business unit at National Semiconductor Corp. in Sunnyvale, Calif., also questions the need for a Class-T. Even the envisioned large commercial satellite constellations such as Teledesic with hundreds of satellites will not generate sufficient volume to justify a single dedicated flow, Edwards claims. The only company so far that has taken steps in that direction, he points out, is Harris Semiconductor in Melbourne, Fla.
Officials of power IC manufacturer Unitrode`s of Merrimack, N.H., also are less than enthusiastic about Class-T. Judy Petersen, Unitrode`s product marketing manager for hi-rel products, says she doubts her company would make any of its power components for the military market to this specification. The company has found excellent profit margins in its 38510 Class-S space parts and is in the process of getting DSCC certification for Class-V. Petersen also raises doubts about Class-T definitions, saying they still need more work.
Class-T boosters
Despite widespread apathy in industry, Class-T is essential to achieve the economies of scale needed by the commercial space industry, insists Jim Knott, a scientist at Hughes Space & Communications, who also operates out of Warwick, R.I., and heads the space parts working group of JEDEC.
Knott maintains that agreeing on widely used part types would enable the semiconductor firms to optimize their flows to meet the needs of four out of five OEMs and result in what he calls a common inventory and common flow that would also reduce cycle times.
Although he stresses the need to reduce the cost of components - by 75 to 90 percent below Class-V for such projects as Teledesic - Knott says he also worries about lead times, which he says can run out to 24-32 weeks if the manufacturers do not have wafers available.
Companies like Hughes are standardizing their spacecraft into a few all-purpose bus configurations that can be tailored to users` requirements, which should result in the need for fewer part types.
One possibility is to use technology from the automotive electronics industry, and Knott questions what he calls the "myth" that all automotive parts are customized application-specific integrated circuits (ASICs) and the idea that space is a more hostile environment than automotive usage.
However, Joe Chapman, government relations manager at the Texas Instruments Military Products Division in Midland, Texas, says that the auto makers generally retain the rights to source control drawings for parts designed to meet their needs. These are not all ASICs, he adds.
Vehement critics
Perhaps the most outspoken critic of Class-T is Leon Hamiter, president of the Components Technology Institute in Huntsville, Ala., and former manager of the components engineering group at the NASA Marshall Space Flight Center.
Hamiter cites the provisions in the original DSCC draft for amending MIL-PRF-38535E dated April 16 in preparation for the May JEDEC meeting that would allow manufacturers of Class-T devices to define their own flows within their quality management plans.
Even though the draft requires the companies to be certified QML suppliers and to develop their Class-T flows through their technical review boards, Hamiter says this still gives them broad latitude in defining their own test methods. They only have to notify the OEMs of any major changes they make to the devices or processes.
Hamiter does not mince words: "This is probably one of the worst mistakes ever made for a government spec for space qualification." He calls Class-T a deterrent to maintaining the supply base for space-qualified parts. Furthermore, he says it will fragment the market and drive out today`s Class-V suppliers.
Nonetheless, Hamiter concedes that the potential savings at the parts level could be significant. He says Class-T parts would be two to three times the cost of a Class-N part, Class-Q would be eight to 10 times the cost of a Class-N part, and Class-V would be 20 to 50 times the cost of a Class-N part.
Although DSCC officials will not release details of their letter seeking responses from NASA and the Air Force, it is known that the purpose of Class-T is to meet the needs of a commercial/military dual-use satellite industry, specifically unmanned satellites, and not for what are considered critical space applications.
Radiation issues
Any Class-T parts also would likely have to meet the radiation requirements of MIL-STD-1019 (total dose). Another rationale, according to Knott at Hughes, is that some OEMs are already using commercial plastic parts in space.
Regarding the radiation issue, although space-qualified parts have traditionally required tolerances in the megarad level. Anthony Jordan, product line manager at UTMC, notes that Q and V levels already allow 100 to 300 kilorads.
John O`Boyle, who is in charge of radiation issues at National Semiconductor, estimates that a spacecraft with a 100-mil-thick aluminum skin could operate successfully in most space environments for 10 years with parts qualified to 100 kilorads. Furthermore, O`Boyle points out, power requirements for components in space systems are dropping - from 3.3 volts to 2.5 volts now and soon to 1.8 volts.
Another issue is spacecraft reliability, which is coming under increasing scrutiny following the on-orbit failures of the Galaxy 4 personal pager satellite in May and a direct broadcast satellite in July, both using Hughes HS601 spacecraft buses.
Critics of any relaxation of specifications, such as Hartman from Analog Devices and Hamiter of the Components Technology Institute, raise the question of increased insurance costs for commercial satellites.
The 80CRH196 Microcontroller from UTMC and similar devices already meet commercial space radiation requirements, say UTMC officials.
