Electroless plating, selective

Manufacture of Printed Wiring Boards. Printed wiring boards, or printed circuit boards, are usually thin flat panels than contain one or multiple layers of thin copper patterns that interconnect the various electronic components (e.g. integrated circuit chips, connectors, resistors) that are attached to the boards. These panels are present in almost every consumer electronic product and automobile sold today. The various photopolymer products used to manufacture the printed wiring boards include film resists, electroless plating resists (23), liquid resists, electrodeposited resists (24), solder masks (25), laser exposed photoresists (26), flexible photoimageable permanent coatings (27) and polyimide interlayer insulator films (28). Another new use of photopolymer chemistry is the selective formation of conductive patterns in polymers (29). 

Miscellaneous Techniques. Lasers have been used for both electroless and electrolytic plating selective dissolution has hcen used from ancient times to give the appearance of a thin plated coaling nf precious metal and mercury layers plated onto the surface of analytical electrodes serve as liquid meial coatings... 

Electroless plating. This process involves autocatalyzed decomposition or reduction of a few selected metastable metallic salt complexes on substrate surfaces. The reaction should be carefully controlled to avoid potential decomposition of the metal film thus formed and to control the film thickness. The induction period of the reaction can be appreciable and an effective way of reducing the period is to preseed the substrate in advance with nuclei of the metal to be deposited in an activation solution [Uemiya et al., 1990]. 

In selected cases two different metals can be codeposited onto a substrate by electroless plating. Shu etal. [1993] have attempted simultaneous deposition of palladium and silver... 

The technique of electroless plating is in principle attractive for industrial applications because of its unique advantages over conventional electrolytic plating. These advantages include (1) the ability to deposit a metal on catalyzed nonconductive substrates, (2) the ability to plate substrates with complex shapes at a uniform metal thickness, and (3) the ability to selectively deposit a metal on catalyzed areas of the substrate surface only. Because of these advantages, industry has found a number... 

Ion chromatographic analysis methods ensure speed and high precision in the analysis of main components as well as of reaction and decomposition products in electroplating baths. The advantage of ion chromatography relative to the partly unspecific wet chemical methods utilized so far lies in the selectivity of the stationary phases and the detection systems being used. Thus, in most cases sample preparation is limited to a simple dilution with de-ionized water and subsequent filtration. A variety of applications on the basis of electrodeposition and electroless plating is summarized in Table 8-3. 

Deposition initiates only on exposed (non-overmolded) "first shot" catalyzed resin areas. Second shot (non-plateable) material is "non receptive" to electroless plating. The resulting selective metallization is shown in Figure 7. 

Similar to photolithography, subsequent processing steps are required to define features. For this reason, j,CP is also typically limited to the fabrication of electrodes in bottom-contact OTFTs. The subsequent processing steps can be classified into three categories selective etching [29,33-35], selective electroless plating [36-39], and selective chemical and electrochemical polymerization [40-43]. Depending on... 

While tCP and selective etching can potentially replace costly photolithographic tools in OTFT fabrication, expensive deposition tools are still required to deposit the metal layers. Recently, a lower cost metal electroless plating deposition technique has been explored as a potential replacement for the more expensive sputtering and evaporation processes. 

In a selective electroless plating, a conductive film of copper or nickel is deposited onto a specific part of the molding as opposed to overall plating by conventional techniques that require paint finishing. Attenuation levels of 50 dB can be obtained at layers of 1-3 microns. 

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