Electroplating Tank Lines

A well compounded ebonite free from carbon black and hygroscopic ingredients and with its surface in a clean condition has a very high resistivity both through the mass of the material, and over its surface. It is so far above what is required for most practical purposes that it is seldom necessary to measure these properties, especially in cases of electroplating tanks lined with ebonite required in most steel plants. 

The majority of anodizing is performed using process equipment similar to chat found in electroplating. Tanks are typically rubber, plastic or lead-lined steel (which may also serve as the cathode) in the case of sulphuric acid mild steel tanks are preferred for chromic acid. The vigorous oxygen evolution during anodizing creates a fine acid mist which requires effective ventilation and/or... 

A nickel electroplating line uses a dip-rinse tank to remove excess plating metals from the parts. Currently, a single tank is used that requires R gal/h of fresh rinse water to clean F parts/h (see Figure 107). Assume the cleaning is governed by the following equilibrium relation ... 

A wide spectrum of process operations is seen in electroplating. Both jig and barrel plating may be carried out in a line plating operation (where the workpiece is moved automatically in a predetermined fashion from one tank to another, including precleaning and postplating operations) or a more flexible (and labour-intensive) vat plating may involve manual movement of the workpiece between the tanks. 

The first series of products developed and commercialized were the solvent processable resists called RISTON I. A 24" wide conveyorized spray developer was fabricated that used 1,1,1-trichloroethane (methyl chloroform) as the developing solvent. After development, the PWB panel was then ready for etching or electroplating. Following that, it was necessary to strip away the polymerized resist. Methylene chloride or azeotropes with methanol were the iiutial stripper chemistries and DuPont fabricated 24" conveyorized equipment to perform that operation. The developer and stripper equipment both fabricated from stainless steel, required in-line solvent stills that would continuously feed a fresh supply of clean distillate solvent through a series of spray chambers and in a counter flow direction to that in which the boards were traveling. Smaller fabricators often stripped using a series of dip tanks. 

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