Current information to electroless nickel

 

Lead and cadmium free : these en processes according to EU standards 2000/53/EG (automobile), 2002/95/EG (RoHS), 2002/96/EG (WEEE), 2003/11/EG 
Tarnish preventive EN-20: If it is tempered without a protective gas above 300 °C for obtaining a higher degree of hardness, electroless nickel layers tarnish. The application of Tarnish preventive EN prevents discolourations up to 450 °C! Protective gases are no longer necessary. Result: Reduction of tempering times by higher temperatures and the surface remains as deposited.
Wetting agent EN-2 and Wetting agent EN-20: The application of wetting agents in electroless nickel baths is necessary in order to avoid pores but also to counter bad smells by means of a blanket of foam. In addition, a decrease of the surface tension is effected in the electroless nickel electrolyte whereby the light-off performance and the first deposition (germination) are improved.  
Nickel acetate bath : Due to the usual hydrogen ion development the acetate changes to acetic acid which escapes with an increasing working temperature from the electroless nickel bath. The MAK value of 25 mg/m3 air is exceeded. Problems to health might be caused for the operating personal.
Zinc and aluminium in electroless nickel : The influence of zinc and aluminium in electroless nickel is known due to zincate treated aluminium surfaces. Two possibilities produce a relief: Either an application of a stabile electroless pre nickel bath (approx. 55 °C) or novel, surface selective components, which bind zinc and aluminium and to remove it from the electroless nickel bath.
Accelerator for electroless nickel : Is effective in contaminated as well as in electroless nickel bath with a lot of salt quantity. By applying the accelerator the deposition speed increases from 2 to 5 µm/h follows.
pH correction without ammonia and carbonate : Hydroxide, actually 130 g/L NaOH, is the alternative to ammonia and carbonate. Under the condition that the electroless nickel system works with this pH correction, I can recommend adequate processes for fast depositing as well as for high-phos baths without cutbacks for the individual functionality ! 
The passable and known problems with ammonia and also with carbonate applications belong to the past.
pH correction without ammonia is now also possible for electroless prenickel baths and/or for plastic coatings at approx. 40 °C +/- 5 ! In this case with 500 g/L KOH or 500 g/L K2CO3.
aluminium coating : If aluminum being treated with zincate is supposed to be nickel plated, it is not sufficient to have a very agreeable pretreatment, the pH-value is also very decisive in the electroless nickel bath. With the pH ranging between 5.0 and 5.2, a better coverage is achieved. This helps to avoid blisters as well as difficulties in general during the deposition process.
aluminium coating : Examinations showed that specific Al-alloys can be  plated with electroless nickel directly. Therefore it is possible to restrain from zincate treatments. Blisters or various pretreatment difficulties don`t have to be accepted anymore ! On the contrary, only a few pretreatment steps presumably synchronized suffice for a perfect electroless nickel plating.

 

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