Anaheim, CA -- February 28, 1996 -- At the NEPCON West trade show today, Teradyne introduced a second-generation version of its popular MultiScan™ vectorless test toolset for Z1800-Series board test systems. Called MultiScan II, the enhanced toolset features a new capacitive coupling technique: FrameScan Plus™. FrameScan Plus expands the fault coverage of the original FrameScan product to include detection of reversed polarized capacitors.

"Reversed capacitors are a serious problem because powering up a board can cause them to explode, resulting in damage to the board and risk to the operator," said Dominic Haigh, product manager. "FrameScan Plus is a power-off technique that can find misoriented capacitors without applying power to the board. Running a FrameScan Plus test before powering up the board allows users to avoid potential damage or early field failures."

In addition to performing polarity testing for capacitors, FrameScan Plus is now the primary MultiScan technique for testing connectors and sockets. FrameScan Plus can also be used to test devices in cases where neither the DeltaScan™ analog junction test or WaveScan™ magnetic induction test provides fault coverage. Together, FrameScan, DeltaScan, and WaveScan provide the most comprehensive vectorless-test fault coverage available today on a single test platform.

How FrameScan Plus Works

FrameScan Plus uses an overclamp fixture mounted over the board-under-test. The overclamp fixture is built with a sensor positioned over each device to be tested. A multiplexer board is mounted in the overclamp fixture; one multiplexer boards supports up to 64 sensors. Up to 16 multiplexer boards can be added to a fixture, supporting up to 1024 sensors.

FrameScan Plus can be used in two modes: either as a standard capacitive coupling vectorless test or to test polarized capacitors for correct orientation. A standard FrameScan Plus test works by: 1) Sending a stimulus signal from the standard Analog Test Board (ATB) in the Z1800-Series tester through the bed of nails to the pin of the device-under-test. 2) The stimulus couples through the device-under-test to the sensor mounted in the overclamp fixture above the device. A buffer amplifier on the sensor ensures maximum sensitivity, accuracy, and reliability. 3) The multiplexer board then switches the buffered signal back to the ATB for measurement. Detected signals go through the standard fixture interface with no external cabling.

To test polarized capactitors: 1) An AC stimulus is applied to the expected location of the cathode connection. This should couple efficiently to the sensor, thus producing a large signal. The received signal (V1) is measured. 2) The stimulus and ground connections are then swapped, so that the inside node of the capacitor carries the AC signal, and the received signal (V2) is measured again. Since this is shielded from the sensor by the now-grounded "can" of the capacitor, the measured signal will be very small. 3) The two measurements are compared in a ratio. If the first measurement is larger (V1/V2 >1), then the capacitor is correctly oriented.

DeltaScan & WaveScan Enhancements

MultiScan II includes improvements to the DeltaScan analog junction technique, providing higher fault coverage, faster debug, and improved test repeatability. Improvements are:

• Multiple vendor test database support eliminates false failures due to vendor variation.
• DeltaScan AutoProbeCheck verifies proper fixture contact.
• Improved program generation for devices such as Lattice GALs and ISP logic.
• Automatic fixture wiringverification.
• Option to log full test data per pin. MultiScan II also includes enhancements to the WaveScan magnetic induction system that increase test throughput.

Pricing & Availability

Teradyne's MultiScan tools are included in the price of all new Z1800-Series testers at no extra charge. MultiScan II will be standard in all Z1800-Series shipments starting in January. Upgrade packages are available for Z1800-Series testers equipped with the original MultiScan toolset or for older Z1800-Series testers without any type of MultiScan vectorless test.