Electroless deposition applications

Electroless deposition as we know it today has had many applications, e.g., in corrosion prevention [5-8], and electronics [9]. Although it yields a limited number of metals and alloys compared to electrodeposition, materials with unique properties, such as Ni-P (corrosion resistance) and Co-P (magnetic properties), are readily obtained by electroless deposition. It is in principle easier to obtain coatings of uniform thickness and composition using the electroless process, since one does not have the current density uniformity problem of electrodeposition. However, as we shall see, the practitioner of electroless deposition needs to be aware of the actions of solution additives and dissolved O2 gas on deposition kinetics, which affect deposit thickness and composition uniformity. Nevertheless, electroless deposition is experiencing increased interest in microelectronics, in part due to the need to replace expensive vacuum metallization methods with less expensive and selective deposition methods. The need to find creative deposition methods in the emerging field of nanofabrication is generating much interest in electroless deposition, at the present time more so as a useful process however, than as a subject of serious research. 

A number of books [10, 11] and book chapters [12-15] are available on the subject of electroless deposition. In this chapter, discussion will center on some of the fundamental and practical aspects of the electroless deposition process. Emphasis will be somewhat biased towards applications relevant to microelectronics. Electroless deposition on fine conductors, which are usually of smaller dimension than the dif-... 

Electroless deposition should not be confused with metal displacement reactions, which are often known as cementation or immersion plating processes. In the latter, the less noble metal dissolves and eventually becomes coated with a more noble metal, and the deposition process ceases. Coating thicknesses are usually < 1 pm, and tend to be less continuous than coatings obtained by other methods. A well-known example of an immersion plating process that has technological applications is the deposition of Sn on Cu [17] here a strong complexant for Cu(I), such as thiourea, forces the Cu(I)/Cu couple cathodic with respect to the Sn(II)/Sn couple, thereby increasing the thermodynamic stability in solution of thiourea-complexed Cu(I) relative to Sn(II). 

A discussion of the applicability of the MPT model to a particular electroless system ideally presumes knowledge of the kinetics and mechanisms of the anodic and cathodic partial reactions, and experimental verification of the interdependence or otherwise of these reactions. However, the study of the kinetics, catalysis, and mechanistic aspects of electroless deposition is an involved subject and is discussed separately. 

Nonvacuum electrodeposition and electroless deposition techniques have the potential to prepare large-area uniform precursor films using low-cost source materials and low-cost capital equipment. Therefore, these techniques are very attractive for growing CIGS layers for photovoltaic applications. 

Chemical processing industries (CPI) application of surfactants in, 24 119 electroless deposition in, 9 699-700 energy and, 10 134-137 24 165-167 environmental impact assessment and, 10 228-229 German, 24 253—254 globalization of, 24 263 heat pipes in, 13 237-240 hydrogen in, 13 797-798 materials and processes in, 24 167-176 metrics for assessment in, 24 179 natural gas in, 12 383-385 quality control in, 21 159-164 regional economic patterns in,... 

More recently, another application of SECM detection in DNA and protein chips and in electrophoresis gels has emerged with different detection principles. Wang et al. [81] labeled single-stranded DNA (ssDNA) with gold nanoparticles. After binding to their complementary strand at the chip surface, silver was electroless deposited at the... 

Electroless plating — An autocatalytic process of metal deposition on a substrate by reduction of metal ions from solution without using an external source of electrons. It is promoted by specific reductants, namely formaldehyde, sodium hypophosphide, sodium boro-hydride, dialkylamine borane, and hydrazine. Electroless deposition has been used to produce different metal (e.g., nickel, cobalt, copper, gold, platinum, palladium, silver) and alloy coatings. It can be applied to any type of substrate including non-conductors. Some substrates are intrinsic catalytic for the electroless deposition other can be catalyzed usually by sensibilization followed by Pd nucleation also, in some non-catalytic metallic substrates the electroless process can be induced by an initial application of an appropriate potential pulse. In practical terms, the evaluation of the catalytic activity of a substrate for the electroless deposition of a given metal is... 

Kohli, N., Hassler, B.L., Parthasarathy, L., Richardson, R.J., Ofoli, R.Y., Worden, R.M., Lee, I. (2006). Tethered lipid bilayers on electrolessly deposited gold for bioelectronic applications. Biomacromolecules 7 3327-35. 

In spite of such limitations associated with the application of the mixed potential concept, results of electrochemical investigation of the partial reactions are highly useful to understand the characteristics of electroless deposition processes. 

Y. Okinaka and T. Osaka describe the fundamental aspects and technological applications of autocatalytic metal deposition processes. In view of that electroless deposition has found important applications in the manufacture of microelectronic devices, a review of the pertaning electrochemical fundamentals has been long overdue. 

Another approach to the direct deposition of platinum onto the membrane surface has been adopted by several workers in exploratory studies of electrochemical processes at the Pt/ionomer membrane interface. Takenaka and Torikai [31] and later Fedkiw and Her [32] and Aldebert and others [33] developed various electroless deposition techniques for the application of a film of platinum to the surface of an ionomeric membrane. The original method suggested by Takenaka and Torikai [31] was based on exposure of one side of the membrane to an anionic salt of the metal... 

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