Cadmium Plating Over Aluminum: Smart Fix for Blistering

Summary for cadmium plating over aluminum Discussion

Cadmium plating over aluminum is discussed in the context of a blistering problem on aluminum and aluminum die castings used for connectors. Kamlesh M. Bhatt of Amphenol Interconnect India asked for a cleaning cycle for electroless nickel undercoat, cadmium overcoat, and olive green passivation on 6061 aluminum die castings and 7075-T6 aluminum. Ted Mooney, P.E. replied that instead of trying to define a perfect universal plating cycle, it would be more useful to describe the actual cycle currently being used and identify where the blisters appear. He noted that ideal cycles may not exist, may be better found in books than forums, and may not fit the realities of the parts, geometry, equipment, and floor space. His practical advice is to narrow the problem first so others can suggest a workable fix from a smaller set of possibilities.

2007

Q. Dear Sir,

I read your site it is very interesting.I have some question for regarding my plating line hope you will throw some light on it. Myself Mr. kamlesh M.Bhatt. Having 20 years exp. in electroplating.We are in the field of manufacturing connecters in India Company as Amphenol Interconnect India Pvt. Ltd.

I want to know cleaning cycle over aluminum & aluminum die castings for Electroless Nickel plating as undercoat & cadmium plating as overcoat followed by olive green passivation.Aluminum die casting used of 6061 grade & aluminum used of 7075 T-6 .We are facing Blistering problem.

Please suggest cleaning cycle for both the processes.

Regards,

K.M.Bhatt.

Dy. MANAGER.

KAMLESH M.BHATT.
Manufacturing all types of connecters.r – PUNE, MAHARASTRA, India

A. Hi Kamlesh. Rather than asking people to describe perfect plating cycles (which may not exist, and which are better described in books than public forums anyway, and which may be impractical for you to install considering the realities of your parts, their shape, your existing installation, and available floor space), please try to tell us the cycle that you use and where the blisters seems to occur. Then people can hopefully narrow down from a hundred broad possibilities to some tenable solutions. Thanks.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey

Need quick confidential answers? $25
Need project assistance? $100/hr.

2007

Q. Cleaning cycle degreasing T-C-E -10-15 MIN SOAK CLEAN

sodium carbonate

⇦ on

eBay or

Amazon]
– 30-35 G/L 2 MIN.

trisodium phosphate

⇦ on

eBay

Amazon [affil link]
30-35 G/L

TEEPOL 2-3 ML/L

RINSE PLAIN WATER 30 SEC -1 MIN

DESMUTTING

NITRIC ACID 95 % 1.5-2 MIN

HYDROFLUORIC ACID 5 %

RINSE PLAIN WATER 30 SEC-1 MIN.

ZINCATING ALBOND DIP ( CMP ) 100 % 1-1.5MIN

RINSE PLAIN WATER 30SEC-1 MIN.

NITRIC ACID NITRIC ACID 80 % 1 MIN.

RINSE PLAIN WATER 30SEC. -1 MIN

DESMUTTING

NITRIC ACID 95 % 1.0-1.5 MIN

HYDROFLUORIC ACID 5 %

RINSE PLAIN WATER 30 SEC-1 MIN.

ZINCATING ALBOND DIP ( CMP ) 100 % 20-30 SEC

RINSE PLAIN WATER 30 SEC- 1 MIN

E. NICKEL (MID PHOS) ATOTECH 15-20 MIN 2.5-3 MIC

RINSE PLAIN WATER 30 SEC-1 MIN.

CADMIUM PLATING

METAL:25 G/L T.CN :150 35- 40 MIN 10-12 MIC

RINSE PLAIN WATER 30SEC 1 MIN

O.5 % NITRIC NITRIC ACID 30 SEC.

OLIVE GREEN ATOTECH 30 35 SEC.

DRY 5 MIN

OVEN TEST 150 DEGREE 1 HR.

BLISTERS OBSERVED IN KNURLING AREA & FLANGE IN CASTING WHERE DARK CASTING MARKS INSIDE MOSTLY BLISTER SIZE IS MICRO ONLY CAN BE SEEN IN 10 X MAGNIFICATION.

PL. SPECIFY ANY PROCEDURE OR SPEC FOR CHECKING CADMIUM PLATED PARTS.

THANKS,

K.M.BHATT.

Kamlesh
– Pune, Maharastra, INDIA

A. If I read the verbal description correctly, the problem appears to be in recessed areas like the knurled area. So I would strongly suspect the cleaning cycle.

I think what I would do is to scrub a number of parts with pumice

⇦ on

eBay or

Amazon [affil link] and a tampico brush before starting the cleaning cycle, and monitor whether this improved cleaning solves the problem. If it does, perhaps an improved proprietary soak cleaner will be a good production tool. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey

Need quick confidential answers? $25
Need project assistance? $100/hr.

2007