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Hull Cell Procedures

June - 2014
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The Hull Cell is a miniature plating unit designed to produce cathode deposits on a panel that correlates the characteristics of the planting unite being evaluated. Interpretation of the “as plated” cathode panel give rapid information about brightness levels, irregular plate deposits, uniformity of deposits, coverage, throwing power, impurities, and plating bath chemistry. Within the parameters of recommended operating characteristics of a particular plating solution the Hull Cell will duplicate what is actually occurring in the plating unit proper. Correlation of the “as plated” panel and hull cell scale allows rapid nondestructive testing of plating solutions for research, preventative maintenance, troubleshooting, and quality control. Steps to performing a hull cell test: 1. A representative sample from the plating unit to be evaluated is withdrawn and should be a composite sampling from carious areas in the plating tank and from various depths within these areas. 2. The representative sample should be analyzed chemically for those critical components recommended by the supplier of the plating bath. Correlation of Hull Cell panels without the information on the bath chemistry can be very misleading. 3. Particular attention should be given to the physical conditions of the plating unit at the time of sampling and these operation conditions should be duplicated during Hull Cell testing. If this is not done, interpretation will be meaningless. Example: temperature, cathode agitation, air agitation. 4. A bench or portable miniature plating cell is employed using the following components: Rectifier with capable controls for amperage from 1-10 volts; Hull Cell anode the same as the plating unit; color coded cables capable of carrying the current required with an alligator clamp soldiered to the cell end; cathode panels of the appropriate substrate; Hull Cell with scribed solution level line 276 ml, 24 ml, or 1000 ml in size; other accessories to simulate the plating unit conditions such as agitators, heaters, etc; and a time ideally build into the DC power unit. Procedure 5.1. Preparation (It is recommended that panels be handled with tweezers and gloves to prevent misleading results.) • Pre-clean cathode test panel. • For zinc plated steel panels: immerse in 50% by volume C.P. Hydrochloric acid to strip off protective zinc film. • Cold water rinse. • Wipe surface with Hull Cell sponge that has been soaked in D.I. water. • Observe panel for water break free condition. Repeat previous 2 steps as necessary. • For plastic coated brass panels-remove plastic film by peeling it off. • Soak in mild soak cleaner. • Reserve current clean at 2 amps for one minute. • Cold water rinse. • Acid dip 10% C.P. Hydrochloric Acid for 5 seconds. • Cold water rinse. • Observe for water break free surface; repeat steps 5.2. Test • Insert cathode test panel along the slanted side of the Hull Cell which has solution to scribed line. • Hook red cable to anode (+). • Hook black cable to cathode (—). • Set timer to prescribed time (see tech bulletin). • Turn on power source. • Adjust power to described amperage. • Start time. • At prescribed time, shut off power. • Disconnect cathode cable. • Remove cathode panel. • Cold water rinse. • Complete desired post plate treatment if any- example: dipping panel in 1/4 to 1/2 of 1% by volume. Nitric .Acid (C.P. Grade) for 3-5 seconds enhances the ability to interpret the panel on zinc and cadmium plating solutions. • Warm Water Rinse. • Dry, forced air or even wiping with a water absorbent paper towel. • An alternate method of drying the panels is to water rinse followed by an alcohol rinse to drive off the water. Also, a method of • preserving samples is to spray them immediately with a clear lacquer to prevent oxidation. 5.3. Evaluation • See proprietor’s data sheets utilizing the Hull Cell Scale appropriate for the amperage used as the guide to current densities. • Hull Scale use: place the bottom edge of the “as plated” on the line that matches the amperage plating was performed. The areas on the panel above these numbers are the area of that number’s current density. 6. Notes 6.1. Preventative Maintenance, Troubleshooting. • Depending upon the bath chemistry as analyzed, condition of the panel relative to uniformity, burning, cloud pat terns skip plate, etc., modification by controlled additions can be made to the Hull Cell plating solution and procedures can be repeated. Changes caused by addition to the Hull Cell will duplicate results to be expected by the same proportionate additions to the main plating bath. • Correlations of thickness checks in the controlled time, temperature, amperage cathode panel will also tell the optimum plating range. Republished from : The Institute for Interconnecting and Packaging Electronic Circuits 2215 Sanders Road Northbrook, IL 60062-6135