Neil,
Regarding "...is the coating mechanically separable from the base metal?"
I thought the commission was rather clear on this point in their WEEE/RoHS faq
>From 2.3 (page 17) - underlines are mine
"Homogeneous material means a material that can not be mechanically disjointed
into different materials.
Definitions:
The term "homogeneous" means "of uniform composition throughout". Examples of
"homogeneous materials" are individual types of: plastics, ceramics, glass,
metals, alloys,
paper, board, resins and coatings.
The term “mechanically disjointed” means that the materials can, in principle,
be separated by mechanical actions such as: unscrewing, cutting, crushing,
grinding and abrasive processes.
Examples:
• A plastic cover is a "homogeneous material" if it consists of one
type of plastic that is not coated with or has attached to it or inside it any
other kinds of materials. In this case the limit values of the Directive would
apply to the plastic.
• An electric cable that consists of metal wires surrounded by
non-metallic insulation materials is an example of a "non-homogeneous material"
because the different materials could be separated by mechanical processes. In
this case the limit values of the Directive would apply to each of the
separated materials individually.
• A semi-conductor package contains many homogeneous materials which
include: plastic moulding material, tin-electroplating coatings on the lead
frame, the lead frame alloy and gold-bonding wires."
A coating by its very concept appears to be something that can be mechanically
disjointed from its substrate by grinding.
Of course, the above is not binding (it can be legally disjointed from the base
legislation by means of semantic abrasion).
Regards,
Lauren Crane
Product Regulatory Analyst
Corporate Product EHS
Applied Materials Inc.
Austin, TX 512 272-6540 [#922 26540]
- external use -
"Barker, Neil" <[email protected]>
Sent by: [email protected]
01/15/2008 01:25 AM
To
"'Fred Townsend'" <[email protected]>, "Tarver, Peter"
<[email protected]>
cc
[email protected]
Subject
RE: Zinc passivation vs. Stainless Steel hardware selection
I think you will find that Alodyne is a chromate conversion coating; Alodyne is
one trade name, Alocrom another. The yellow clour comes from the chromium. The
down side is that the jury is out on whether or not such a coating complies
with the RoHS Directive. Is there still hexavalent chromium in the coating, and
is the coating mechanically separable from the base metal? Fortunately there
are clear-coloured alternatives that are definitely free of hex-chrome and that
can be proven to be equally corrosion resistant and equally conductive (there
are also some that are corrosion resistant, but non-conductive).
I agree that coloured anodizing is simply dyed, and you can have almost any
colour you want; black, blue, red, gold, green, etc.
Best regards
Neil R. Barker CEng MIET HonFSEE MIEEE
Manager
Quality Engineering
e2v technologies (uk) ltd
106 Waterhouse Lane
Chelmsford
Essex CM1 2QU
UK
Tel: (+44) 1245 453616
Fax: (+44) 1245 453571
Mob: (+44) 7801 723735
P Please consider the environment before printing this email.
