Metal finishing Q&As since 1989

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Plating peels unless we pre-dip in KCN

2005

CAN ANYONE HELP IN KNOWING THE EXACT REASON FOR THIS?. YOUR REPLY WILL HELP US TO SOLVE A BIG PROBLEM IN PLATING.
WE WERE PLATING NICKEL, GOLD AND TIN LEAD ON CU-SN BASE MATERIAL. WE GET PEELING ISSUE (THE WHOLE PLATING OF NICKEL,GOLD AND TIN LEAD 90/10 PEELS OFF) . THOUGH WE RAISE OUR ELECTROCLEAN CONCENTRATION AND CURRENT WE STILL HAVE PEELING. BUT WHEN KCN IS USED AFTER ELECTROCLEAN AND BEFORE ACID ETCHING THERE IS NO MORE PEELING ISSUE. WE HAVE THIS PROBLEM ONLY ON CERTAIN BATCHES OF OUR PARTS SENT BY OUR CUSTOMER. WHAT I THINK IS, WHEN KCN IS ADDED TO WATER IT DISSOCIATES INTO KOH AND HCN AND THIS KOH REMOVES ANY DIRT OR OIL ON THE PART. IS THIS TRUE. PLEASE ADVICE? WE ARE ADDING 5KG TO 100 liters OF WATER TO MAKE UP OUR BATH.

SIVAKUMAR
PLATING - SINGAPORE

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Hi,
I think your electrocleaning is dirty and KCN take the hand of the oil and smut. Try to change your electrosoak more often mayby eatch second weeek or frequently. Bercause KCN is one of the most effivtive cleaner you can have.

Regards

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
2005

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2005

Sivkumar,
I will add to what Anders said.
Try to introduce soak cleaner prior to electroclean.Temperature maitanance also is important.There is no need to have a KCN dip at all.Carry forword of Cyanide traces to Nickel bath which is acidic will be dangerous.In that place you may go for a 5% sulfuric acid of Hydrochloric acid dip depending on what your Nickel bath consits of.This will neutralize as well as activate the substrate and you can get a proper finish.
But remember to stop using cyanide dip before you try this.
Regards

T.K. Mohan
plating process supplier - Mumbai, India

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Hi Sivakumar,

If your machine is not able to add Soak Clean as proposed by T.K., You may consider to change to different Non Cyanide Electroclean which can remove the oil.

HL Eng
- Singapore
2005