Plating on Aluminum Without Cyanide or Nickel

Prior to the development of EPI's E-Brite Ultra Cu non-cyanide alkaline copper plating process and the development of EPI's E-Prep 280NCZ non-cyanide zincate, aluminum had to receive a cyanide copper strike over a cyanide based zincate. E-Brite Ultra Cu and E-Prep 280NCZ have eliminated the use of cyanide in plating on aluminum.

There were some installations using a zincate plated with nickel to eliminate the cyanide copper strike. However, this technique results in the rapid contamination of the nickel bath with zinc resulting in expensive maintenance of the nickel bath.

The EPI Process:

• Clean: Wrought alloys and extrusions are thoroughly cleaned and degreased for 5 to 10 minutes in a hot (150° to 170° F) solution of EPI's E-Kleen 133 for a heavy etch or E-Kleen 139 for a very mild etch while cleaning. If a non-etching aluminum cleaner is used, see note after this process.
   
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
   
• Deoxidize/Desmut: When an etching cleaner is used, any smut formed during cleaning must be removed with a 1 to 2 minute immersion in a solution of EPI's E-Pik 210 maintained at 65° to 80° F or with a 1 to 2 minute immersion in a 40% by volume room temperature Nitric Acid solution.
  
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
   
• 1st Zincate: Immerse parts in a 25 to 30% by volume solution of E-Prep 280NCZ at 70° to 80° F for the length of time necessary to produce a uniform grayish finish, usually within 30 to 60 seconds, depending upon the alloy.
   
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
   
• Acid Dip: Immerse parts in a 50% by volume room temperature Nitric Acid solution for 10 seconds to 20 seconds to strip the zinc and leave a uniformly clear finish on the surfaces.
   
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
   
• 2nd Zincate: Same as in Step 5 above. The 2nd zincate bath in Step 9 can be a separate solution or the same one used in Step 5.
   
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
  
• Plate: Copper strike plate with E-Brite Ultra Cu.
   
• Rinse: Using a bottom-fed, overflowing cold water rinse for 30 seconds to one minute.
  
• Plate: Plate with E-Brite 200 acid copper or E-Brite 787 bright nickel or with both.

NOTE: If a non-etching aluminum cleaner such as EPI's E-Kleen 130 or E-Kleen 131 is used to remove surface soils prior to etching, a separate etch with EPI's E-Pik 232 will be required. The first steps of the process will then be:

1. Clean with E-Kleen 130 or E-Kleen 131.
2. Water rinse.
3. Etch with E-Pik 232 solution at 130° to 160° F, 1 to 2 minutes.

Then go to Step 2 above and continue the process.

NOTE: Some aluminum castings and alloys may require only one zincate step. Therefore, some experimentation should be done to determine if two zincating steps are required to obtain satisfactory adhesion of the subsequent copper strike.

Complete technical information for the E-Brite Ultra Cu can be found in the Products Section of the Home Page under Plating. Technical data for the E-Kleen 130, 131, 133 and 139 can be found under the Cleaning Section and data for the E-Prep 280NCZ, E-Pik 210 and E-Pik 232 under the Surface Preps and Activation for Metals Section.