Metallic joints, electronic devices

The determination of molecular formulas via accurate mass measurements relies on isotopic masses accurate to at least 1 in 10 [10]. Elemental trace analysis is required for the detection of radioactive nuclides in the environment, of transition metals such as Pt in exhaust fumes from automobiles [11], and in the quality control of low-sulfur fuels for the same. All electronic devices demand for high-purity semiconductors and the properties of alloys are critically influenced by trace elements [12]. Age determinations from isotope ratios are applied in archeology, paleontology, and geology [4,13,14]. More recently, elemental MS and biomedical MS are jointly employed to unveil the presence and preferably location of metals in proteins or DNA as well as their lateral distribution in tissues [15-18], a field of research basically going back to seminal work by Houk in 1980... 

If a constant strain is imposed on a metal or alloy, the stress relaxes with time as the system reduces its free energy. Dislocations are annihilated and the remaining dislocations move to lower-energy configurations. This is the nature of the recovery process. At higher temperatures, diffusional processes equivalent to creep occur. This phenomenon is very important for solder joints in electronic devices because the device spends much time at the strain extremes when it is turned on and off or put into a sleep mode and returned to active duty. Stress at constant strain vs. time curves for Sn-3.5Ag solder at 25 °C and 80 ° C, and at 0.3 % strain maximum are given in Fig. 6(a,b). The stress as a result of the coefficient of thermal expansion mismatches initially decreases very rapidly with time to a more or less steady state value. At 25 °C, the steady state value is about 15 MPa and is rather independent of the initial stress value however, at 80°C, the stress relaxes to zero. Thus when an electronic device is turned on, the thermal stress will relax to a low value possibly zero during use. 

We have seen that in an oxidation electrons are released and that in a reduction they are acquired. In a battery, the release and acquisition are spatially separated. Electrons are released into an electrode, a metallic contact, in one region of the battery, travel through an external circuit, and then attach to the species undergoing reduction at a second electrode elsewhere in the battery. Thus, the redox reaction, the joint oxidation and reduction reactions, proceed, and in doing so, the flow of electrons from one electrode to the other is used to drive whatever electrical equipment is attached to the device. Modern batteries use a range of... 

Fig. 10.1 Metal atom reactor. A - Glass reaction vessel. B - Electron beam furnace, model EBSl, G.V. Planer Ltd. C - Vapour beam of metal atoms. D - Co-condensate of metal and substrate vapours. E - Heat shield. F - Furnace cooling water pipes. G - Electrical lead for substrate solution dispersion device. H - Furnace electrical leads. J - Substrate inlet pipe (vapour). K - Substrate inlet pipes (solution). M - Rotation of reaction vessel. N - To vacuum rotating seal, service vacuum lead troughs and pumping systems. 0-Level of coolant (usually liquid nitrogen). P-Capped joint for product extraction. 0-Substrate vapour dispersion device. R-Substrate vapour beam. (From Green, M.L.H., 1980, /. Organomet. Chem., 300, 119.)...

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