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An RF admittance level sensor uses a rod probe and RF source to measure the change in admittance. The probe is driven through a shielded coaxial cable to eliminate the effects of changing cable capacitance to ground. When the level changes around the probe, a corresponding change in the dielectric is observed.
Typical passive oscilloscope probe being used to test an integrated circuit. A test probe is a physical device used to connect electronic test equipment to a device under test (DUT). Test probes range from very simple, robust devices to complex probes that are sophisticated, expensive, and fragile.
Ideally a gate-level circuit would be completely tested by applying all possible inputs and checking that they gave the right outputs, but this is completely impractical: an adder to add two 32-bit numbers would require 2 64 = 1.8*10 19 tests, taking 58 years at 0.1 ns/test.
A simple example of an effectively random cause in a physical system is a borderline electrical connection in the wiring or a component of a circuit, where (cause 1, the cause that must be identified and rectified) two conductors may touch subject to (cause 2, which need not be identified) a minor change in temperature, vibration, orientation ...
A common form of in-circuit testing uses a bed-of-nails tester.This is a fixture that uses an array of spring-loaded pins known as "pogo pins". When a printed circuit board is aligned with and pressed down onto the bed-of-nails tester, the pins make electrical contact with locations on the circuit board, allowing them to be used as test points for in-circuit testing.
A sudden fail-open fault can cause multiple secondary failures if it is fast and the circuit contains an inductance; this causes large voltage spikes, which may exceed 500 volts. A broken metallisation on a chip may thus cause secondary overvoltage damage. [1] Thermal runaway can cause sudden failures including melting, fire or explosions.
the probe will act as a circuit and affect the results of the test. For this reason, the tests performed at wafer sort cannot always be identical and as extensive as those performed at the final device test after packaging is complete [3] since the probe pads are typically on the perimeter of the IC, the IC can soon become pad-limited.
[1] Usually a very simple device, it normally provides an amplifier, and a loudspeaker, often battery-powered and packaged into a small, hand-held test probe. An optional diode detector is usually also provided, allowing the detection of amplitude-modulated signals. The technician injects a test signal into the device under test. Then, by using ...