Electroless nickel

Electrogalvanizing Electrography Electrogravimetry Electrohydrodynamics Electro-Katadyn process Electrokinetics Electroless deposition Electroless nickel Electroless plating... 

Nickel electroless plating on a less noble metal is common.17 For example, the source of nickel can be nickel sulfate. The reducer can be an organic substance, such as formaldehyde. A chelating agent (tartrate or equivalent) is generally required. The nickel salt is ionized in water ... 

In the case of dissolved metal as major additive compounds, a combination of precipitation and redissolution can be applied for recovery from spent solutions. Gyliene et al. [94] found, for recovery of the main additive in nickel electroless plating, that the Ni(II)-citrate complex could be precipitated with alkali followed by redissolution in citric acid for reuse in electroless nickel plating after separation of the precipitate. Additionally, for decontamination of spent electroless nickel plating solutions Fe(III) can be used to precipitate the pollutant. 

Figure 72 Plastics components with selective copper-nickel electroless coatings for shielding against radio-frequency and electro-magnetic interference (Courtesy of Shipley Europe Limited)...

Much of metal electrodeposition is carried out with the aim of minimizing corrosion, the most common electrodeposits being tin, zinc, nickel and chromium on a cheaper metal substrate, such as iron. Since there is chemical bonding between substrate and electrodeposit, this is better than covering with paint (except electrophoretic painting, see Chapter 15) and additionally the surface generally becomes harder, as it does in nickel electroless plating. 

J.I. Han, S.I. Hong, "Nickel electroless plating process for solder bump chip on glass technology," Jpn. J. Appl. Phys., Vol. 36, 2091-2095 (1997). 

Photoproduced palladium nanoparticles have an average size ca. 3.3 nm that only slightly exceeds the critical size ensuring their stability in the nickel electroless plating bath. As a result, only 30 % of Pd centers of the latent image exhibit dissolution during Ni deposition, while others initiate the Ni plating... 

As a typical example, we can mention nickel electroless plating. The process generally utilizes hypophosphorous acid solution. When iron is immersed into the solution, the metal surface works as a catalyst and promotes the dehydrogenatimi reaction of hypophosphite ion as follows. 

BRIGHT NICKEL BRIGHT ACID COPPER SEMI-BRIGHT NICKEL ELECTROLESS NICKEL... 

A method used to ensure the complete filling of vias is electroless plating of nickel. Electroless plating is a process to plate metal without electrical current involved. As a result, it eliminates the seed layer needed in electroplating. To plate nickel on copper, the copper surface must first be activated in a palladium chloride solution. This activation treatment allows palladium to bond to copper at certain sites so that the subsequent nickel plating can nucleate. 

There are a number of other surface finishes used in the industry, such as Electroless Nickel Electroless Palladium Immersion Gold (NiPdAu), Immersion Silver, Immersion Gold, Immersion Tin, OSP and Electrolytic Nickel Gold. There are reliability and process trade offs with each surface finish. That is why it is recommended that strain/strain rate characterization and thermal cycling be performed for each set of surface finish before it is selected for the specific end-use conditions in which it will be used. The industry test methods used to evaluate different surface finishes are outlined in detail in the next chapter. 

Characteristic Copper Electroplated nickel Electroless nickel Chromium EkclreNss nickel + chremiMB Etedreplaled kkd chromiua rir—mt... 

EnviroMwiM Temperature Corrosion rate Electroless nickel- Electroless pbO( Aonis(a) nidcd-b(Mmi(b) ... 

Polytetrafluoroethylene (FIFE), diamond, and SiC particles can also be incorporated into a nickel electroless plating for improved properties. Diamond and silicon carbide are used to enhance abrasion resistance the surface hardness of these composites is reported to be 1300 HVN. Polytetrafluoroethylene is added to the electroless nickel bath to provide a composite coating with enhanced lubrication. Almost any particulate material can be deposited in a metallic matrix, provided the particles are sufficiently small to remain suspended in the bath and that the particles do not react chemically with the bath during electrodeposition. 

Table 9 Compares the wear and corrosion resistance of electroplated copper, electroplated nickel, electroless nickel, electroplated...

Ihble 11 Compares the Taber abrasion resistance of electroplated nickel, electroless nickel, and electroplated hard chromium... 

Electroless nickel/electroless palladium/immersion gold (ENEPIG)... 

The electroless nickel/electroless palladium/immersion gold (ENEPIG) finish is simply an ENIG finish into which an intermediate layer of palladium (0.1 to 0.5 pm thick) is deposited between the electroless nickel and immersion gold coatings. Palladium is deposited from an autocatalytic plating bath. Palladium is a noble metal applied to protect oxidizable Ni. Palladium (m.p. 1552°C) is not fusible but rather dissolves in the molten solder in a manner similar to gold, and... 

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