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Troubleshooting
Acid Copper Plating Baths
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By and large, acid copper plating baths based on the CLX Maintenance system are are rugged and easy to use. When problems do occur, they are typically easy to analyze and fix without major brain death.

Possible problems that might occur include:

Deposit roughness
  • Anode type: Phosphorized copper (0.04 - 0.08%P) in a sintered polypropylene anode basket is ideal, but polypropylene and dynel bags can also be used. OFHC ("Oxygen-Free High Conductivity") copper is not acceptable since impurities in the material can cause various degrees of anode polarization and suspended particulate matter in the plating solution
  • Anode bags: If you are using anode bags, check for obvious holes by filling with water and allowing it to drain out. Holes, if any, will be VERY obvious
  • Solution clarity: Filtration must be provided in order to maintain smooth deposits. 2 - 10 micron, wound polypropylene filters are preferred. DO NOT attempt to use a household a grade water filter (many of which are wound cotton) as it may react with the acids in the electrolyte.
  • High chloride: Above 125 ppm chloride ion there is a tendency to produce rough, dull deposits and to cause anode polarization through the formation of copper chloride deposits on the surface of the anode. Excess chloride can be removed by adding stoichiometric quantities of silver nitrate (AgNO3) to precipitate chloride. However, this technique MUST be followed by a complete filtration (5 micron filter) of the bath to remove suspended silver chloride particles that might result in VERY rough plating.
  • Low brightener: In extreme cases, low brightener can contribute to roughness. Correct this by analyzing the electrolyte with a Hull Cell and making the additions indicated by the condition of the test plate.
  • Insufficient agitation: Increase the air flow to the sparger manifold. The recommend airflow is 2 CFM of clean, dry air for every square foot of bath area between the anode baskets.

Dullness
  • Brightener shortage: Using the Hull Cell, add Coppergleam CLX Maintenance in small increments (0.10 ml) until desired results are achieved. Replenish main bath with amount indicated by the Hull Cell. Excess CLX Maintenance (up to 3X normal strength) is not harmful and can be beneficial in the presence of organ materials in holding stress levels to a minimum.
  • Low chloride: Less than 20 ppm chloride can result in a dull deposit. Analyze the bath and adjust the chloride level using concentrated (35%) hydrochloric acid.
  • Organic contamination: After significant use (or as the result of an accident) the electrolyte may become contaminated with organic compounds that interfere with the action of the brightening / leveling agents. This will usually manifest itself as dull deposition of copper and/or step (skip) plating around through-holes. In the case of severe contamination, an examination of the anodes will reveal a thick, grayish brown sludge coating the surface. For best results, carbon treat the bath and replenish the CLX Maintenance using the Hull Cell as a guide.

Poor throwing power

"Poor throwing power" refers to the inability of the bath to reliably plate through-holes and blind vias. Some of the causes of this are:
  • High copper, low acid: Check the copper, sulfuric acid, and chloride ion concentrations in the bath and replenish as needed. Excess acid (up to 15% v/v) will increase the throwing power and brightness of the deposition, but may cause precipitation of copper (as copper sulfate) out of solution. Brightener stability is NOT affected by excess sulfuric acid.
  • Brightener shortage: Using the Hull Cell, test for the brightener / leveler (CLX Maintenance) concentration in the bath. Replenish the amount indicated by your analysis of the Hull Cell test plates.

Anode polarization

Anode polarization can be caused by excess chloride ion, close bagging of anodes, organic contamination, or insufficient anode area.
  • High chloride: Above 125 ppm chloride ion there is a tendency to produce rough, dull deposits and to cause anode polarization through the formation of copper chloride deposits on the surface of the anode. Excess chloride can be removed by adding stoichiometric quantities of silver nitrate (AgNO3) to precipitate chloride. However, this technique MUST be followed by a complete filtration (5 micron filter) of the bath to remove suspended silver chloride particles that might result in VERY rough plating
  • Close bagging of anodes: This is not a problem with Think & Tinker plating cells which use proprietary anode baskets of sintered polypropylene.
  • Organic contamination: After significant use (or as the result of an accident) the electrolyte may become contaminated with organic compounds that interfere with the action of the brightening / leveling agents. This will usually manifest itself as dull deposition of copper and/or step (skip) plating around through-holes. In the case of severe contamination, an examination of the anodes will reveal a thick, grayish brown sludge coating the surface. For best results, carbon treat the bath and replenish the CLX Maintenance using the Hull Cell as a guide.
  • Insufficient anode surface area: For optimum bath performance, the anode surface area should be between 2 and 3 times the surface area of the item being plated. Think & Tinker anode baskets, when used in a properly configured plating cell, insure that the optimum ratio is maintained.


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