The environmental test industry has successfully convinced most electronics manufacturers to implement their time-proven stress testing methods for confirming product quality. But the industry is not complacent about its victories because there are new riddles yet to be solved.
The technological challenges for environmental test manufacturers are focused on designing and developing equipment that satisfies the specific needs of the automotive and telecommunications industries. Car manufacturers must have customized environmental test stations to suit specific car models plus the capability to automate the test process, said Sri Welaratna, president and CEO of Data Physics.
For example, Rolls Royce needed to run material-fatigue tests on critical components. Data Physics adapted a controller that helped automate the testing, yet preserved all of the test data for further study and analysis.
“The decades-old environmental test standards are themselves a challenge for today’s technologies,” said Preston Wilson, president and CEO of QualMark. “To encompass the capabilities of newer products, testing conventions must change.”
With today’s time-to-market push, customers want to use in-line systems to test products, according to Tom Patterson, national sales manager at ESPEC. Right now, the cost is prohibitive, but environmental test equipment manufacturers are working on ways to get the price of an in-line system within the budgets of most electronic companies.
Providing water for humidity chambers at clean-room-quality levels isn’t an easy task either, said Mr. Patterson. These chambers must be free of contaminants including alumina, sulfates, and chlorides. They must be chemically clean and pure so chip manufacturers can begin testing and have a base reference point before inducing possible product failures.
Another issue affecting environmental test is the need to test devices at-speed while performing burn-in-during-test, said Motay’s Mr. Rhodes. It demands more power, and it is not easy building systems that can meet this requirement.
Producing leading-edge technology at a reasonable cost is a constant battle for electronics manufacturers, said Dominic Acquarulo, vice president of sales and marketing at Ling Dynamic Systems (LDS). For makers of environmental test equipment, the difficulty lies in convincing potential customers that the vibration equipment is required—not a luxury—if they want to improve the quality of their products.
Technological Breakthroughs
The automated testing-during-burn-in of devices was a significant achievement for customers of memory modules, said James Rhodes, president of Motay. The company’s Unigen® 2000 MemPRO not only automates the testing process, but also provides environmental stresses to a variety of memory modules including DRAMs, SRAMs, EEPROMs, EPROMs, and flash devices.
A significant technological breakthrough for the vibration control and analysis industry is the dramatic reduction in equipment size over the past 30 years, said Mr. Welaratna from Data Physics. For example, the fast Fourier transform analyzer or dynamic signal analyzer used to be a 5’ × 19″ rack. Now it is available as a Type III PCMCIA card for notebook computers.
For consumer electronics and automotive products, environmental testing must use more sophisticated techniques to duplicate field failures, said ESPEC’s Mr. Patterson. For example, automobile electronics are subjected to rapid temperature and humidity changes during normal use, which causes dew to form on them. Ion migration occurs when moisture forms on the electronic circuitry. The ion chain migrates from one circuit trace to another causing a short. ESPEC developed the Dew Cycle Test Chamber to duplicate the dew formation with a system that transitions from high temperature—low humidity to low temperature—high humidity.
Technological changes and advancements for vibration-system amplifiers have been strictly electronics based, said LDS’s Mr. Acquarulo. Water-cooled amplifiers are obsolete, and digital switching amplifiers are the current trend. For digital switching amplifiers, the higher the switching frequency, the cleaner the output signal. The high-frequency switching rate also translates into low distortion at the shaker head.
In 1997, the most dramatic contribution from QualMark was the QHT service mark, according to Mr. Wilson. The mark indicates that a product was subjected to and passed an accelerated stress test and categorized accordingly.
Growth in 1998
“The continuous push in the environmental industry comes from the ever-shorter product life cycles that force manufacturers to get reliable products to market faster,” said QualMark’s Mr. Wilson. “We also are seeing less use of military test standards in favor of commercial standards. In fact, some companies are substituting commercial for military standards.”
The electronics manufacturers have made great strides toward improving the quality of PCBs, said ESPEC’s Mr. Patterson. Companies still perform ESS on electronic products, however, the applications are more specialized. Some of these applications are for stress screening of components, such as disk heads, that need special environmental chambers with pinpoint temperature accuracy.
Today, manufacturers want test data to be available to the designer, the test engineer, and anyone else involved in the overall quality of the product. As a result, environmental test manufacturers must provide equipment with the capability to be networked, said Mr. Welaratna at Data Physics.
The growth areas in environmental test will be the satellite and mobile communications industries, said Mr. Acquarulo at LDS. Products in these markets include cell phones, pagers, satellite black boxes, and the equipment that supports them.
There will be significant growth in accelerated life testing and the equipment that supports it, said Mr. Wilson. HALT and HASS are used more and more because manufacturers want to shorten the time to market yet still maintain reliability of their products.
The automotive industry will be a growth market, especially for manufacturers of equipment for accelerated life testing, said ESPEC’s Mr. Patterson. The automobile makers want chambers that test all products. Unfortunately, different products need different stress and test processes. For example, one product may precipitate 5% failures on a 10° temperature ramp rise, and another needs a 20° temperature ramp rise to precipitate failures.
Any predicted growth in 1998 will not happen if the prices of environmental test equipment are considered to be too high, said Mr. Welaratna. Fortunately, prices for many environmental test instruments will continue downward. For example, controllers that cost $70,000 in 1989 now are as little as $25,000 and more sophisticated. Lowering the cost of the hardware makes testing more accessible to a wider audience.
What to Look for in 1998
The new year will herald enhancements and additions from many environmental test manufacturers. For QualMark, look for further development of the OVS product line as well as enhancements to the controller software. The company also will provide more accelerated testing and humidity screening services.
A new control system will be offered by LDS, said Mr. Acquarulo. It will operate with Windows NT or Windows 95.
“Product introductions from Data Physics will focus on the three Cs: connectivity, consistency, and compatibility,” said Mr. Welaratna. “Connectivity of our products to other systems through a network will make our customers more productive. Consistency also will add to productivity because any feature that operates in the way you expect gives the instrument an intuitive feel.
“Compatibility allows you to exchange information from the test system to the design system and back again. Our products will continue to provide the capability to export data in the same format as other analysis products, such as modal analysis displays or animation programs. The company expects the three Cs to drive the environmental test industry in 1998,” Mr. Welaratna concluded.
Environmental Test Products
Chamber Has Slide-Out Features
For Triaxial Vibration Table
The QRS™-600V Power Screen System consists of a thermal chamber with separate heating and cooling compartments and a triaxial, quasirandom vibration system. Programming, operation, and control are facilitated with the SSC-2000 Controller. The shaker table employs 16 pneumatic actuators. Vibration levels of 30 g rms are attainable, and loads up to 600 lb are accommodated. The temperature chamber provides transition rates to 60° C/min. Screening Systems, (714) 855-1751.
Thermal System Meets
International Standards
The TP04200A ThermoStream System meets EU, UL, VDE, SEMI, and CSA thermal requirements with a temperature range from -80°C to +225°C. The air heating and cooling capacity is 9 liters/s continuous airflow, and the temperature control is 0.1°C. Applications include testing components, hybrids, and modules and provide thermal profiles for multichip modules, PCBs, and small subassemblies. The ATE-compatible unit has IEEE 488, RS-232, and ST/EOT/SOFF interfaces. Temptronic, (617) 969-2501.
Environmental Handler
Accommodates SMDs
The T-7500H SMD Environmental Handler tests surface-mount devices such as PQFP, SOIC, and BGA. It provides a throughput of up to 1,200 units/h at zero test time. A multi-color, active, matrix flat-panel display with a touch screen is used for the GUI. The handler maintains temperatures in a range from +25°C to +155°C with a ±2°C accuracy. Thermonics, (408) 496-6838.
Shaker Rated at 2,000 lb Force
For Sine and Random Tests
The DS-2000 Shaker is a compact vibration system rated at 2,000 lbf for sine and random tests. It features a 2″ peak-to-peak movement for low-frequency, high-displacement tests. The 12″ dia magnesium armature provides acceleration levels >60 g. The company’s dynamic centering system with optical sensors ensures that the armature remains centered during travel. The system accommodates automotive squeak and rattle testing, military transportation testing, and ESS applications. It is air cooled and supports payloads to 700 lb. Thermotron¸ (616) 393-4580.
Closed-Loop Control Software
Puts Data in Time Domain
Time Replication Acceleration Control is a closed-loop method for electrodynamic shakers that allows reproduction of acceleration data in the time domain. It is available as an option for the company’s UD-VWIN vibration control system. The software stores up to 10 minutes of acceleration time waveforms and zooms from 1 frame to 1/8 frame. Applications include buzz, squeak, and rattle testing; accelerated life testing; endurance testing, and environmental conditioning. Unholtz-Dickie, (203) 265-3929.
Enhanced Software Offers
Fatigue/Production Testing
The DP550Win Version 3.0 Vibration Control Software includes fatigue testing in sine control, an enhanced production test set in shock and transient, and SRS testing for compliance with the Bellcore standard for earthquake, office, and transportation vibration. Also included are improvements in random control to detect open-loop conditions during self-test. Connectivity across a network is simplified so you can make your own interface elements and interact with the DP550Win SignalCalc Vibration Controller from a remote location. Data Physics, (408) 371-7100.
Burn-In System Offers
Automated Memory Test
The Unigen® 2000 MemPRO 2435 is an automated memory-test-during-burn-in system for DRAMs, SRAMs, EPROMs, EEPROMs, memory modules, and flash devices. Single- or dual-chamber configurations are available with 96 burn-in board (BIB) positions per system. Each 48-position chamber has four 12-BIB-position signal zones. A Pentium-based computer drives the system. Specialized data acquisition and control modules provide chamber management functions and connect the computer to patented drivers to manage multiple DUT input signals and test sequences. Motay Electronics, (602) 961-0654.
Switching Power Amplifier
Minimizes Distortion
The SPA-K Switching Power Amplifiers with power ranges of 5 to 50 kVA in 5-kVA increments are designed for use with the company’s air-cooled shakers. A microprocessor control unit and an LCD function display accommodate setup and troubleshooting operations. Current-sharing capability of better than 1% allows multiple units to be connected in parallel. Distortion is <0.15% at full power. The amplifiers comply with European and U.S. safety and EMC regulations. Ling Dynamic Systems, (800) GO TO LDS.
HALT System Designed
For Small Products
The OVS-1.5 Highly Accelerated Life Test (HALT) System combines an 18″ × 18″ vibration table with a small footprint for testing smaller products. It provides a maximum of 80 Grms and thermal change rates up to 60° per minute. The system uses 208-VAC power and can operate with portable liquid nitrogen tanks. The chamber requires an air supply of 20 scfm for maximum vibration conditions. QualMark, (303) 254-8800.
Chambers Test
Dew Formation
The Dew Cycle Test Chambers provide controlled temperature and humidity environments. A control panel allows up to six operation patterns to be programmed and graphically displays testing conditions. A defrost function makes continuous operation possible. The DFTH-70 provides a temperature range of 20°C to 70°C at 60% to 95% RH. The DFTH-200 offers a -10°C to +30°C temperature range at 40% to 80% RH. ESPEC, (800) 537-7320.
Copyright 1997 Nelson Publishing Inc.
December 1997