Where the
world gathers for metal finishing
Q&As since 1989


-----

Cleaning for aluminium cycle to avoid blisters

February 14, 2009

WE ARE PLATING CADMIUM PLATING OVER ALUMINIUM AND ALUMINIUM DIE CASTING USING ELECTROLESS AS UNDERCOAT. WE ARE USING 6061 AND 7075 ALUMINIUM MATERIAL. 6061 MATERIAL COMES FOR PLATING AS EXTRUSION . wE ARE FACING PROBLEM OF BLISTERS AFTER OVEN TEST. BLISTER WHAT WE OBSERVE IS A PIN HOLE SIZE. WE HAVE NOT OBSERVE BLISTER BIGGER IN SIZE. WE HAVE TESTED MATERIAL FOR POROSITY AND MICROPOROSITY OBSERVED WITH THE MATERIAL.cAN YOU PUT YOUR SUGGESTIONS ON THIS WHETHER POROSITY WILL LEAD TO BLISTERS AND HOW TO AVOID?

oUR CLEANING CYCLE FOR COMPONENT IS DEGREASING (TCE), SOAK CLEAN,RINSE, DESMUTTING (HNO3 95% + 5 %HF ) +RINSE.ZINCATING( CMP-ALBOND DIP),RISE,80% HNO3 ( STRIP),RINSE, ZINCATING,RINSE, ELECTROLESS NICKEL 15 MIN. MID PHOS, RINSE, CADMIUM PLATING 40 MIN. RINSE, O.5 % HNO3,O.G. PASSIVATION, RINSE,RINSE, DRY.

THANKS,

KAMLESH BHATT
PLATING SHOP - PUNE, MAHARASTRA, INDIA

---

March 6, 2009

Your pretreatment is not adequate for treating 7000 series aluminum.

You also may check if your EN is not stressed.This may also a cause of blister problems , even when you've done a good pre-treatment.

I believe your local electroplating supplier can supply the right process for you.

Gabriel Schonwald
Bnei Berak, Israel