Use in electrical and electronic equipment

• Author: Clemm, Christan; Löw, Clara; Baron, Yifaat; Moch, Katja; Möller, Martin; Köhler, Andreas R; Gensch, Carl-Otto; Deubzer, Otmar
• Pages: 18-23

RoHS Annex II Dossier, final

Five cobalt salts

18

2. USE IN ELECTRICAL AND ELECTRONIC EQUIPMENT

All five cobalt salts (cobalt dichloride and cobalt sulphate, cobalt dinitrate, cobalt carbonate and

cobalt diacetate) are used in surface treatment processes. The EEE specific uses in surface

treatment processes are electroplating and metal passivation.

• In relation to electroplating, in the ECHA background documents of 201128 technical or

decorative or magnetic plating is mentioned.

According to the preliminary investigation regarding the conditions of use of the five soluble

cobalt salts, ECHA (2013)29 stated that the cobalt salts are used in metal alloy plating

processes: “The main process reported is gold-cobalt alloy electroplating, although other

processes, such as zinc-cobalt, nickel-cobalt, nickel-cobalt-copper, tin-cobalt, etc., have also

been identified. Cobalt sulphate appears to be the preferred cobalt salt for gold-cobalt

electroplating, together with cobalt carbonate in very small amounts. Cobalt sulphate is also

reportedly used in a large number of other cobalt alloy electroplating applications, while cobalt

dichloride appears to be used for tin-cobalt and zinc-cobalt coatings specifically. Although no

information has been provided regarding the interchangeability of the cobalt salts in

electroplating applications, it might be inferred that, similar to the passivation processes, the

choice of cobalt salt can affect the characteristics of the final coating. Specific surface

characteristics such as ductility, grain size, etc. are referred to in the information supplied, which

appear to be cobalt salt-specific.”

According to ECHA (2018b)30, “metallic alloy coatings produced by electroplating are used for

example in the jewellery and the watchmaking industry.”

• In metal passivation, an anti-corrosion layer/coating is achieved. According to Association of

Equipment Manufacturers AEM:31 “some formulations also contain cobalt chloride (to give harder

coatings).”

According to ECHA (2013), cobalt dichloride, cobalt sulphate, cobalt dinitrate and cobalt

diacetate are used in the generation of conversion layers in passivation processes: “Cobalt

dinitrate appears to be the most commonly used cobalt salt for this application, accounting for

more than half of the total use of cobalt salts in passivation. According to the information

supplied in the consultation, each cobalt salt provides specific characteristics to the protective

coating (colour, optical appearance, thermal and corrosion resistance, etc.) and can influence

the speed of the passivation process. However, due to the limited information available, it is not

possible to draw a firm conclusion as to whether the cobalt salts will be readily interchangeable

from a technical or economic perspective in passivation applications.”

28 Op. cit. ECHA (2011 a and b)

29 Op. cit. ECHA (2017a); from page 41 on as last part the following report is included: ECHA (2013): A preliminary

investigation into the conditions of use of five cobalt salts final report July 2013, public version.

30 ECHA (2018b): Restriction report Annexes; Annex XV Restriction Report, Proposal For A Restriction, Substance

Names: cobalt sulphate cobalt dinitrate cobalt dichloride cobalt carbonate cobalt di(acetate);

https://echa.europa.eu/restrictions-under-consideration/-/substance-rev/21805/term, last viewed 18.02.2019

31 AEM Association of Equipment Manufacturers (2018): Contribution submitted on 15.06.2018 during the stakeholder

consultation conducted from 20 April 2018 to 15 June 2018 by Oeko-Institut in the course of the study to support the

review of the list of restricted substances and to assess a new exemption request under RoHS 2 (Pack 15);

http://rohs.exemptions.oeko.info/fileadmin/user_upload/RoHS_Pack_15/1st_Consultation_Contributions/Contribution

_AEM_Cobalt_chloride_sulphate_20180615_RoHS.PDF, last viewed 16.07.2018