As discrete resistors, capacitors and inductors are being displaced by film deposits on substrates and dissimilar semiconductor devices become “integrated,” how can component testers keep up with these changes? By adding new features, expanding measurement ranges and making greater use of computer power, they not only meet the technological challenges but also satisfy today’s higher throughput demands.
Testing Passive Components
Of course, there are still millions of passive components being produced each week to serve the many needs that cannot be handled by thin film or silicon infusion, either because of power or size limitations. Testing these discrete components as well as many of the composites is still best performed by conventional RLC meters. However, many of these meters now perform measurements over extended frequency ranges and are operated in conjunction with PCs.
Programming an RLC meter over an RS-232 or GPIB computer interface simplifies setup, commented Mayrose Gaoiran, sales and marketing engineer at Stanford Research. It also facilitates automatic operation of the instrument, whether used alone or in conjunction with other equipment.
PC control of RLC meters is becoming very common in production environments, first for establishing component test conditions and secondly for automated datalogging, added Jim Richards, marketing engineer at QuadTech. To simplify these tasks, we provide LabVIEW® drivers with our instruments.
Components with unique characteristics or produced in large quantities often are tested best with task-oriented instruments. Transformers and chokes (inductors) used in switch-mode power supplies (SMPS) are a case in point.
“The critical tests for these components typically are inductance (L) and (Q), DC resistance, turns ratio, leakage inductance, interwinding capacitance, DC bias current (0 to 100 A) and insulation resistance (determined at up to 500 VDC),” said Ken Harrison, national sales manager at Wayne Kerr. “To perform these tests with precision and high throughputs, a new breed of automatic impedance analyzers had to be developed.
“In the case of transformers with multiple connections, a switch matrix is needed under GPIB control. However, it is vital that any losses in the switching system are compensated (trimmed) at the correct operating frequency. For best results, Kelvin connections must be used to provide the desired measurement accuracy,” Mr. Harrison concluded.
Kelvin connections are adequate for precise measurements of two-terminal devices as long as the component of interest is not shunted by nongermane circuitry. But many passive devices today are part of an integrated network on a substrate. In this case, the DUT may be shunted by one or more components and isolating it electrically requires the use of a 6-wire ohms measurement technique.1
For some complex or composite components that must be measured in a single test operation, even a 6-wire measurement capability may not be adequate. “For example, integrated RC and RL networks not only require 6-wire ohms testing, but also mixed AC and DC signal source/measure facilities,” said Mark Cejer, strategic marketing manager at Keithley Instruments. “To perform speedy multiple signal interconnections with required precision at DC and at frequencies up to the RF range, fast, low-loss, wide signal bandwidths switch cards are best.
“Typical of these are isolated coaxial multiplexer cards using long-life dry-reed relays that have very low contact resistance and low contact potential,” Mr. Cejer continued. “These types of cards, which may be plugged into instruments or into separate cages, handle up to 1 A of current at about 40 V. With switching times below 1 ms, these cards help increase test throughput without degrading accuracy.”
High Current, High Voltage and Active Components
Components used in automotive and industrial electronic assemblies as well as those used in circuit protection applications often must accommodate or withstand high currents or high voltages. For production testing of these devices, which include resistors, thermistors and varistors, the source and measurement units must be suitable for fast single-channel, go, no-go measurements at relatively high, as well as at very low, levels.
“Typical tests include resistance checks at a specified voltage or current, breakdown voltage and insulation resistance evaluation and characterization,” commented Mr. Cejer. “Voltages can go as high as 1,000 V or more and current requirements can go up to 3 A or more. Communications equipment, for example, commonly uses varistors for EMI and ESD protection which require testing up to 1,000 V to simulate transients caused by lightning strikes.”
Some component testers are readily reconfigurable or expandable. The Testronics Model 201 Test System, for instance, has a basic configuration with ratings up to 200 V/20 A and down to 10 pA/100 µV. This range can be extended in both directions, programmable power sources can be added and pin-out can be expanded.
“The increasing breadth of technical requirements, such as higher power for some parameters and lower voltage and current for others, has prompted us to offer measurement options to 1-fA resolution with both 200-A and 1,000-A power sources up to 2,000 V,” said Noel Kelley, president of Testronics. “Often, these source and measurement circuits must be located on the adapter or in the test head to be as close as possible to the DUT.”
To provide high throughput, the 201 is linked directly to the ISA bus of the PC via a special interface card. “Using this data interchange method vs relying on parallel or serial port communication, we can increase the data rate necessary for high-speed testing of today’s components,” explained Mr. Kelley.
“Moreover, using the PC and modems help the testers to become part of the corporate system of operation. Programs can be centrally generated and controlled and be network-accessible, data can be uploaded and downloaded from remote sites, remote calibration and diagnosis become feasible, and continuous statistical analysis and process control are facilitated,” Mr. Kelley concluded.
SZ Testsysteme testers which accommodate devices ranging from discrete single-function ICs to mixed-signal LSIs and VLSIs are not PC-based but use workstations. According to Hans Giessibl, marketing manager at SZ Testsysteme, workstations offer greater acceptance for complex tasks by the semiconductor industry and multinational log-in operational and debugging support.
“Competitive forces in consumer electronics drive the semiconductor industry to combine an increasing number of functions which once were performed by discrete single chips into systems-on-silicon,” said Mr. Giessibl. “This approach not only is being applied at the LSI and VLSI high end of the IC spectrum, but also for relatively low integration ICs.
“For example, an automotive dashboard controller that until the middle of last year consisted of three chips on a hybrid multi-chip-module now is a single IC. The original three devices were so unlike each other that they required different test facilities:
Chip 1 was the serial interface device between the CPU, decoder and pulse width modulator needed for analog displays. Test demands included serial interface and output response checks to 20 MHz, preferably performed by a digital tester.
Chip 2 was the power driver for the meter coils, display and lamps. The mix of digital logic interface and medium power tests were best handled by a smart power tester.
Chip 3 performed voltage-regulator functions requiring load regulation, dropout voltage, over-voltage, surge protection, short circuit and reverse battery tests all performed best by a linear tester.
To perform such varied tests on a single device in one pass, new types of multifunctional mixed-signal test equipment are being developed. The SZ M3650/10, for instance, uses a tester per-pin architecture and combines new analog-pin electronics with a 200-MHz digital test capability to facilitate fast high-speed parallel measurements. The tester also handles current up to 300 A and voltage up to 2,000 V and has femtoamp measurement capability.
Trends
More passive components are being produced using thin film on silicon and component manufacturers will use this technology to create more complex devices consisting of both passive and active components, predicted Mr. Cejer. The level of integration and component densities will continue to increase in step with the growth of application-specific circuits. This will intensify the need for instruments that can perform precise tests on relatively inaccessible (buried) passive components.
For active component testers, in addition to providing the needed test resources at a reasonable test-cost/device rate, test equipment mean time between failure (MTBF) and mean time to repair (MTTR) will become more important selection criteria. As ATE becomes part of the production operation, a failed test system gravely impacts realizable output and can even require shutting down a production line.
Greater use will be made of diagnostic software to minimize outages. Also, software is playing a continuously larger role in making today’s complex testers simpler to program and operate, commented Mr. Kelley. The tester’s hardware must have the capabilities to perform tests the components require, but software often is an equally determining factor in the ultimate selection process.
References
1. Cejer, M., “Automotive Electronics Environment Increases Need for Fast, Accurate Tests,” EE-Evaluation Engineering, March 1997, pp. 30-37.
Note: This article can be accessed on EE’s TestSite at www.nelsonpub.com/ee/. Select EE Archives and use key word search.
Component Tester Products
Multifrequency RLC Meters
Offer High Precision
The 7400 and 7600 Precision RLC Meters simultaneously measure and display two of 14 parameters. The 7400 operates from 10 Hz to 500 kHz and the 7600 from 10 Hz to 2 MHz, both with an accuracy of ±0.05%. Component parameters may be displayed as a function of conditional (or swept) measurement variables, such as test frequency, voltage or current. Automated test sequencing, calibration and binning are provided. Up to 50 test setups may be stored internally. A 3-1/2″ disk drive and interfaces for IEEE 488.2, RS-232, a printer port and a handler are standard. QuadTech, (800) 253-1230.
LCR Meters Perform Over
100-Hz to 100-kHz
Range
The SR700 Series LCR Meters measure R+Q, L+Q, C+R and C+D at frequencies ranging from 100 Hz to 100 kHz. The SR715 has a basic accuracy of 0.2% and the SR720 has an accuracy of 0.05%. Three drive voltages and five source frequencies may be selected. Up to nine instrument setup configurations can be stored and recalled. Automatic binning and limit features, and RS-232, optional GPIB and parts-handler interfaces facilitate production testing. SMD and Kelvin clips are optional. Stanford Research Systems, (408) 744-9040.
Inductance/Transformer Analyzer
Suited for High-Speed Testing
The TTS System consists of the PMA3260A Precision Magnetic Analyzer, a switching matrix and PC software. It tests inductors/transformers at frequencies up to 500 kHz (3 MHz optional). Inductors may be tested for L, Z, RDC, C, Q, D, RAC and phase angle. Transformer tests include RDC for each winding, primary inductance and Q, turns ratio, interwinding capacitance and leakage inductance. Up to 30 tests may be selected and stored as a test sequence for any transformer. Wayne Kerr Electronics, (617) 938-8390.
Discrete Device Tester
Provides High Throughput
The Model 5300HS is an automatic tester for discrete semiconductors including IGBTs, MOSFETs, diodes, optos, transistors, triacs, zeners, SCRs, regulators, diacs, SSOVPs, relays, J-FETs, MOVs, quadracs and sidacs. It features high-speed datalog, intuitive PC programming, real-time math, statistics reports and lot summaries. Source/measurement capabilities offer off-state to 2 kV (5 kV optional), on-state 50 A (to 1,200 A optional), resolution to 1 pA and 1 mV. Options include multiplex, scan, inductive tests, various device adapters and fixtures. Scientific Test, (972) 487-9421.
Crystal Impedance Meters Offer
125 ms/Device Measurements
The HP E4915A and E4916A wide-frequency (1 to 180 MHz) crystal impedance meters use the transmission PI-network method to measure the characteristics of crystal resonators, including resonant frequency, resonant impedance and equivalent circuit parameters. The HP E4915A provides crystal and spurious measuring modes; the HP 4916A also offers variable output power and drive-level-dependency measurements with evaporation monitoring filters. Options 001 and 010 add 1- to 180-MHz LCR measurement capabilities. Hewlett-Packard, (800) 452-4844.
Fifth-Generation Tester
Provides High Throughput
The 201C Component Test System accommodates high-volume testing of components, such as transistors, diodes, FETs, relays, resistors, capacitors and inductors. A new measurement module features a 16-bit ADC and a high-speed I/O module and bus scheme. Operating software includes pull-down menus and windows with a test language optimized for 486 and higher performance PCs. Software filters enhance system capabilities for performance of fast, low-level leakage measurements. Real-time processing of delta calculations speeds datalogging. Testronics, (972) 542-3111.
System Facilitates Op-Amp
Tests With Femtoamp Input Bias
The functionality of the M3610 Mixed-Signal Testsystem platform has been extended with a test solution for standard and precision op-amps accommodating low input/bias or high voltages (up to 200 V). A quadruple measurement loop with programmable compensation facilitates parallel setup and low settling times. The new current loop eliminates thermal electromotive force errors. SZ Testsysteme, (408) 744-0793.
New Instrument Class Provides
Wide Source/Measurement Ranges
The Model 2410 high-voltage SourceMeter® and the Model 2420 high-current SourceMeter® combine precision voltage/current sources with a high-resolution digital multimeter and measurement firmware. They are suited for high-volume production testing of resistors, networks, RF diodes, displays, varistors, solar cells and hybrids. Model 2410 generates source voltages from ±5 µV to ±1,100 V and measures from ±1 µV to ±1,100 V. Model 2420 sources current from ±500 pA to ±3A and measures current from ±l00 pA to ±3A. Keithley Instruments, 800-552-1115.
Copyright 1997 Nelson Publishing Inc.
April 1997
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