Chemical deposition copper

Nair, M. T. S. Guerrero, L. Arenas, O. L. Nair, P. K. 1999. Chemically deposited copper oxide thin films Structural, optical and electrical characteristics. Appl. Surf. Sci. 150 143-151. 

Coating of polymer surfaces with thicker metal layers (10-30 pm) is a much more complicated operation. Several pre-treatment steps are required first the polymer surface has to be modified in such a way that, by a chemical process, a layer of copper or nickel can be deposited. With ABS use is made of the circumstance that it is a two-phase system, consisting of a hard matrix in which rubber particles are dispersed. The rubber particles present at the surface, are etched away, leaving a rough, porous surface, which offers a good adhesion to the chemically deposited copper or nickel. Thereafter the application by electrolysis of further layers of other metals (e.g. chromium) is simple. Also for PP, PMMA and polyamides, methods have been developed for chemical deposition of the first metal layer. 

I Swept Field. Wire Current Reset after Each Transition. - Chemically Deposited Copper. Coating Thickness 0.0006 in Diameter. 

Fig. 5. Effects of chemically deposited copper and various holders on Nb25%Zr wire.

Chemical deposits of copper are applied to provide conducting surfaces on non-metallic materials. 

Chemical deposition Simple immersion deposits of copper may be obtained on iron and steel in a solution containing, for example, 15 g/1 of copper sulphate and 8 g/1 sulphuric acid, and on zinc-base alloy in a solution containing copper sulphate 300 g/1, tartaric acid 50 g/1 and ammonium hydroxide 30ml/l . Such deposits are thin and porous and are mainly plated for their colour, e.g. for identification, or for their lubricating properties, e.g. in wire drawing. 

Pathan, H. M. Lokhande, C. D. 2005. Chemical deposition and characterization of copper indium diselenide (CISe) thin films. Appl. Surf. Sci. 245 328-334. 

In the other stndy, Cn S was chemically deposited on (presnmably evaporated) CdS films from a triethanolamine/ammonia/thionrea bath (see Chap. 6, copper snlphides) [2]. Very low currents and poor fill factor were obtained, al-thongh the Voc was reasonable (ca. 0.5 V), with an efficiency of ca. 0.5%. The stoichiometry of the Cu-S was not ideal for PV cell nse, althongh this conld be varied to an extent by electrochemical treatment. 

The most popular method involves deposition initially of a layer of electroless copper up to 2 /an thick. The excellent conductivity of the copper ensures that this gives good results for attenuation (that is, for shielding). The copper layer is followed by electroless nickel up to 1 /an thick, which protects against abrasion and corrosion. Obviously it is important that the nickel not be porous and with this in view an activation stage may be interposed, with chemical deposition of palladium on the surface of the copper in preparation for the nickel. 

Fig. 10.27 Plating of via using PEDT (a) chemically deposited MnO, and (b) and (c) electrochemical deposition of PEDT and copper in the via.

Replacing the platinum electrodes with copper, and adding some CuSO, changes the situation radically. Passing a current between the electrodes causes no net chemical change (copper is dissolved off one electrode and deposited on the other). In this case current is observed as soon as a potential, small as it may be, is applied to the electrodes. 

The possibility of applying copper deposition directly on top of TiN barrier via electrochemical method was studied. Previous report of using contact displacement to deposit copper was found chemically questionable. The copper deposition observed could be due to reaction between cupric ion and silicon underneath through cracks in the intermediate TiN layer. 

Studies were made with wire which was initially imcoated and then coated with either chemically deposited or electrolytically deposited copper. The results are shown in Figs. 4 and 5. The data in Fig. 4 for the plated condition with chemical and electrolytic deposition, respectively, and the unplated condition are so consistent from sample to sample that only one curve is shown through the points. It can be seen that the addition of 0.0003 in. of copper on the radius has not affected the performance of the wire in any way. 

Chemically deposited and electroplated copper with a radial, coating thickness of 0.003 to 0.001 in. has no effect upon the transition current for the wire at a given field. The enhanced stability of a copper-coated wire after a transition has occurred has been demonstrated by producing a condition in which the tip of a hairpin of wire has undergone a transition and the normal region has not propagated from the tip along the sides of the specimen. 

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