Electroplating plastics

Cjcolac Brand MBS Electroplating, Technical PubHcation 402, GE Plastics, Pittsfield, Mass., 1990. 

American Society of Electroplated Plastics, Standards and GuidelinesforElectroplatedPlastics, 3rd ed., Prentice-HaU, Inc., Englewood Cliffs, N.J., 1984. 

Nickel—2iiic batteries containing a vibrating zinc anode lias been reported (83). In this system zinc oxide active material is added to the electrol 1 e as a slurry. During charge the anode substrates are vibrated and the zinc is electroplated onto the surface in a unifomi mamier. Tlie stationary positive electrodes (nickel) are encased in a thin, open plastic netting which constitutes the entire separator system. 

Specifications and Test Methods. The American Society of Electroplated Plastics pubHshes a comprehensive book covering most technical aspects of testing and control (24). A number of ASTM standards have been issued that cover thickness, adhesion, and thermal-cycling resistance of the total plated film. Some specifically for plated plastics include ... 

The first commercial boards usiag electroless plating for connection between the sides were made by Motorola ia 1953 (41). An unclad plastic board was coated with electroless silver, a reverse resist appHed, and copper electroplated to the required circuit thickness. The resist and excess silver were removed. This semi-additive process is stiU used, with copper replacing the silver. 

Although metals and alloy substrates account for much of the volume ia electroplating, there is a large and growing amount of plastic surfaces being plated, both for decorative trim and for electronic shielding appHcations. On a smaller scale, other materials that ate plated iaclude wood (qv), plaster, fibers (qv) and cloth materials, and plant and animal tissue, such as leaves, leather (qv), paper (qv), and seasheUs. 

A.STM B533, Std. Test Methodfor Pee/ Strength of Metal Electroplated Plastics, American Society for Testing and Materials, Philadelphia, Pa., 1992. 

Nowadays, however, zinc-coated steel sheets, either continuously galvanised or electroplated, are often used as a basis material for overcoating with plastic materials or paints. The coatings are usually applied continuously and have a range of uses both externally and internally. Many surface finishes are obtainable, e.g. plain or embossed, and in an extensive range of colours, to suit almost any requirement . 

Chemical reduction is used extensively nowadays for the deposition of nickel or copper as the first stage in the electroplating of plastics. The most widely used plastic as a basis for electroplating is acrylonitrile-butadiene-styrene co-polymer (ABS). Immersion of the plastic in a chromic acid-sulphuric acid mixture causes the butadiene particles to be attacked and oxidised, whilst making the material hydrophilic at the same time. The activation process which follows is necessary to enable the subsequent electroless nickel or copper to be deposited, since this will only take place in the presence of certain catalytic metals (especially silver and palladium), which are adsorbed on to the surface of the plastic. The adsorbed metallic film is produced by a prior immersion in a stannous chloride solution, which reduces the palladium or silver ions to the metallic state. The solutions mostly employed are acid palladium chloride or ammoniacal silver nitrate. The etched plastic can also be immersed first in acidified palladium chloride and then in an alkylamine borane, which likewise form metallic palladium catalytic nuclei. Colloidal copper catalysts are of some interest, as they are cheaper and are also claimed to promote better coverage of electroless copper. 

After special pretreatments, specific grades of plastics can be put through electroplating processes similar to those used in the plating of metals. Electroplated plastic products are very durable and provide... 

A survey of applications was also done by Czichocki et al. [73], including such applications as inks and paints, paper, photography, plastics, emulsion polymerization, pharmaceuticals, flotation, corrosion inhibitors, lubricants, electroplating, electrophoresis, and catalysts for ethoxylation. 

Electroplating is the electrolytic deposition of a thin film of metal on an object. The object to be electroplated (either metal or graphite-coated plastic) constitutes the cathode, and the electrolyte is an aqueous solution of a salt of the plating metal. Metal is deposited on the cathode by reduction of ions in the electrolyte solution. These cations are supplied either by the added salt or from oxidation of the anode, which is made of the plating metal (Fig. 12.16). 

---