Electrical testing techniques

L.D. Pitts, "Electrical Probe Technique for Measurement of Detonation and Deflagration Velocities , 4thONRSympDeton(1965), 616-26. In these experiments the probe consisted of a length of resistance wire sandwiched between two strips of insulating material. After placing the probe adjacent to the wall of the metallic test cylinder, a constant current was forced thru the probe. Detonation, or deflagration front pressure... 

The case of isopropyl alcohol used in processing ICs is an example of chemical quality specifications. A manufacturer sent the laboratory two bottles of two different lots of isopropyl alcohol. With one lot, the manufacturer produced ICs that passed all electrical tests. With the other lot, the ICs failed. After these two materials were analyzed side by side with a variety of wet chemical techniques, it was found that the two lots differed only in potassium content. Both samples contained potassium in quantities well within SEMI specifications, but one contained almost 10 times as much potassium as the other (10 ppb versus 100 ppb). 

Testing techniques for the evaluation of physical properties and other properties of finished margarine products as well as low-fat spreads have been stated to include (4, 91) appearance, oral melting characteristics, oil exudation, slump (collapse), penetrations, spreadability, emulsion viscosity at 35°C (95°F), emulsion drop size, and electrical conductivity. 

But first, although the importance of careful sampling of any product that is to undergo testing is self-evident, very special precautions must be taken in the case of insulating oils (ASTM D-923, IP 51), for which special techniques are recommended. Precautions that are stipulated are mainly concerned with the avoidance of contamination that would affect electrical tests. 

Electrical Cell-substrate Impedance Spectroscopy (ECIS) measurements based on Oscillation-Based Test techniques... 

The microfabrication of electrode arrays built with silicon micromachining techniques illustrates an positive approach towards future Cl electrode array development in respect to the traditional manufacturing method used now days. Also lithography and MEMS technology facilitates the addition of enhanced functionality to the microelectrode arrays. There is, however, still a long way to go until these devices can be used in real Cochlear Implants. The fabrication possibilities and characterization of different CMOS compatible metals (Ti, TiN and Al) provides a strong base to go ahead with further research in this direction. In our electrical tests done we conclude that TiN is able to withstand a high current density 2.8, while aluminium failed... 

Jiirgen Czarske and Lars Biittner Faculty of Electrical and Computer Engineering, Laboratory for Measurement and Testing Techniques, Technische Universitat Dresden, Dresden, Germany... 

Most of the test methods described in this chapter are based on the test manual IPC-TM-650. It contains industry-approved test techniques and procedures for chemical, mechanical, electrical, and environmental tests on aU forms of printed wiring and connectors. An IPC test method is a procednre by which the properties or constituents of a material, an assembly of materials, or a prodnct can be examined. These test procedures do not contain acceptability levels for specific properties. 

Proposals have circulated for radical new measurement approaches to electrical testing. These have included the use of electron beams, laser-stimulated photoelectric effects, and gas plasma techniques in configurations similar to existing flying probers. In each case, the board is scanned without use of a custom test fixture. To date, all of these methods involve compromise of fault coverage, or add little or no fine-pitch performance beyond conventional methods. Relaxation of test criteria is not a relief available to most users. HDI product types demand increased fine-pitch capability. These finer trace and via geometries increase the risk of latent defects and increase interest in measurement methods most sensitive to precursor symptoms of such defects. As a result, none of these approaches has seen widespread adoption. 

Defects are most often detected by visual inspection or automated optical inspection (AOI). Other means of nondestructive evaluation (NDE) include electrical testing, x-ray inspection, and ultrasonic inspection. The preferred NDE inspection technique for BGA and CSP solder joints is x-ray inspection. Automated x-ray inspection equipment is often placed directly into the assembly process line for circuit board products having a large number of area-array components. 

Many techniques have been developed to measure the Young s modulus and the stress of the mesoscopic systems [12, 13]. Besides the traditional Vickers microhardness test, techniques mostly used for nanostructures are tensile test using an atomic force microscope (AFM) cantilever, a nanotensile tester, a transmission electron microscopy (TEM)-based tensile tester, an AFM nanoindenter, an AFM three-point bending tester, an AFM wire free-end displacement tester, an AFM elastic-plastic indentation tester, and a nanoindentation tester. Surface acoustic waves (SAWs), ultrasonic waves, atomic force acoustic microscopy (AFAM), and electric field-induced oscillations in AFM and in TEM are also used. Comparatively, the methods of SAWs, ultrasonic waves, field-induced oscillations, and an AFAM could minimize the artifacts because of their nondestructive nature though these techniques collect statistic information from responses of all the chemical bonds involved [14]. 

The direct measuremoit of the sq>aration between two bearing surfeces of metal-on-metal hip implants tested in a hip simulator under normal walking conditions was carried out by Dowson et al (2000) using the above electrical resistance technique. The mode of lubrication in flieir experimental study was mixed, with some periods of very effective surface separatioi and others of metal-on-metal contact in each simulated walking cycle. Using the same technique, Smith et al (2001a) have demonstrated surface separation of the femoral head and acetabular cup by a lubricating film in ceramic-on-ceramic hip implants. However, it was not clear whether protein films enhanced the sur ce separation in both of these studies. 

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