Artistic Plating Featured in Products Finishing Magazine for Expansion in Medical Industry
Artistic Plating to once again Exhibit at 2012 Medical Design and Manufacturing Show in Minneapolis, MN
Artistic Plating Launches Expansion of Precision Tin/Lead and Lead Plating Lines
Artistic Plating Expands with New Flagship Heavy Build Copper Plating Line
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Plating And Underplate SelectionWhat are the advantages of electroless nickel over traditional electrolytic nickel? Electroless nickel (EN) has several distinct advantages over electrolytic nickel deposits. EN is an amorphous alloy of nickel and phosphorous. The addition of phosphorous provides the deposit with more corrosion resistance, less magnetic properties and a low coefficient of friction. The application of post-plate heat treatment causes the formation of nickel phosphides at grain boundaries which hardens the deposit. Because the deposit doesn't require the application of an external electrical reduction force (DC rectifier or power supply) to create the deposit, but uses a chemical reducing agent within the solution chemistry, the deposit is extremely uniform in thickness. The plate is uniform across diameters, across threads and in dead end holes. This property often eliminates the need for post-plate machining on critical dimensions. Figure F.3 below shows two cross-sectional photos of two identical gears, one plated in electroless nickel and one plated in electrolytic nickel. The drastic improvement in uniformity of the deposit is very clearly seen. The top photos show the teeth of the gears, the bottom photos show the inner bore of the gear. Note that EN plates completely within the bore. Figure F.3: Electroless Nickel Verses Electrolytic Nickel
In summary, the advantages of EN are: Why should bright tin not be used for solderability? Bright tin is deposited from an acidic solution. The brightening system used is typically based on naphthalene compounds. These organic compounds codeposit with the tin. When the deposit is soldered, the temperature exceeds that required to oxidize the organic portion of the deposit and the codeposited brighteners burn. This is seen as a blackening or darkening on the surface of the deposit or solder joint. This charring prevents the formation of a proper solder joint. To prevent this, the tin deposit must be devoid of codeposited organics. This is done in the plating systems which do not use any organic brightening systems. These processes are generically called "solderable" and plate out as a dull, matte finish, but they are highly solderable. (back to top) What type of nickel plating should I use for my application, watts, bright or sulfamate? Nickel plating is an important electro deposition process for preserving steel, brass and other basis metals from corrosion. Plated as a bright deposit often combined with chromium, nickel is the most effective electroplated coating for preserving a decorative appearance for extended periods of time in corrosive environments. Nickel electro deposition is also popular for engineering applications as a non-decorative functional plate. Bright nickel electroplated for decorative uses differs appreciably from non-decorative nickel deposits. The high sulfur content (>0.05%) of the bright deposit reduces its ductility and corrosion resistance. Bright deposits are typically deposited from the watts formulation (see below) with the addition of organic-sulfur "brightening systems." Engineering deposits are typically deposited from the watts bath less brighteners (commonly referred to as watts non-bright) or from sulfamate chemistries (see below). Brightness in nickel deposits is induced with organic-sulfur compounds that decompose at cathode surfaces forming very small particles of nickel sulfide which refine the grain size of the deposit at the cathode surface by at least two orders of magnitude. The selection of brightener additions to the plating bath affects ductility, internal stress, electrical conductivity and corrosion resistance of the deposit, all in a negative manner. Nickel coatings stressed in tension reduce the fatigue strength of steel. Nickel deposits lose corrosion resistance, ductility and electrical conductivity as the amount of co-deposited sulfur or other impurities increases from the brightening system. The change of the above characteristics is a rather complex subject which is primarily dependent on the bath chemistry, but also to a lesser extent on the operational parameters of that chemistry. The following charts will provide general trends/properties of nickel as deposited from the three (3) traditional chemical systems: watts non-bright, watts bright (watts with organic brighteners) and sulfamate.
Corrosion Resistance: The corrosion resistance of nickel deposits is very complex and the object of much study. In general, as any impurity is added to the deposit, the nickel plate loses its ability to fight off corrosion. The most common deposit impurities are hydrogen, oxygen, carbon, sulfur, chloride and metallic impurities. Because the watts non-bright and sulfamate formulations do not co-deposit sulfur and carbon from a brightening system, they are more corrosion resistant. In summary, for engineering applications where ductility and corrosion resistance of the deposit take precedence over a decorative finish, a watts non-bright or sulfamate formulation is the deposit of choice. If low internal stress is also a concern for parts that will be significantly deflected or bent, sulfamate nickel processes are superior. However, bear in mind that these deposits are not bright and as such do not have as high of an aesthetic appeal. The old adage “bright is right” does not always apply for engineered coatings! What type of tin plating should I use for my application? Tin plating is provided in two general types of deposits, bright and matte. Both can be obtained from an alkaline or acidic bath. The acidic chemistries are most common today. The advantages of each type are as follows: Bright Tin Matte Tin How do I make a solderable deposit? Electroplating is often used to produce a clean, pristine metal surface upon which to solder. Many of the electrodeposited metals are capable of being soldered upon. These include gold, silver, nickel, electroless nickel, cadmium, copper and tin. If the soldering is to be performed on the ultimate layer, this layer must be kept devoid of oxidation and transient surface contaminants. Because this is difficult to do, the most common scheme to promote solderability is to deposit the surface upon which to solder as the penultimate layer and then top coat with a metal that will amalgamate into the solder (tin, gold or silver). The best known version of this is to copper plate or nickel plate a substrate and then apply a matte tin as the final coating. The matte tin should be devoid of any codeposited organics from the electrolyte. Artistic Plating can provide additional information on this subject if desired. (back to top) Why should I use gold or silver on my contact system? The use of precious metals (gold, silver, palladium) on electrical circuits makes use of the superior electrical properties of this group. These properties, coupled with the innate corrosion resistance of the precious group, provide a combination that has long provided the "Cadillac" of performance in electrical design and requirements. No other metals will perform as well as gold and silver in electronic circuits and power distribution networks. They also have the added characteristics of lubricity, solderability and reflectivity. |
FINISH SELECTOR Gold Plating CERTIFICATIONS
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