kevin...
An excellent discussion of the various grades and uses of
oxygen free copper is on MjrWebsites, hosted on Angelfire.
The author seems to be an audio engineer, since the subcontent
which includes this discussion of copper is a subset of his
page which has a design for a new breed of audio amplifier.
That page is here:
http://www.angelfire.com/ab3/mjramp/index.html
The page which discusses grades of copper is here:
http://www.angelfire.com/ab3/mjramp/golopid/ofc.html
It is first noted that 'oxygen free' is a misnomer, since
some oxygen remains, and that 'oxygen reduced' is a more
accurate term.
Oxygen reduction is accomplished as follows:
"Deoxidised copper is produced by several different methods,
one being to use a deoxidising agent such as phosphorus:
BS C106, ISO-CEN Cu-DHP has low enough oxygen for welding,
and is commonly used for tubes, extrusions etc. The fairly
high phosphorus content however reduces conductivity typically
15% below that of ETP. The copper purity is about the same as
ETP, but phosphorus is at about 200ppm."
"A better grade, Cu-DLP has reduced phosphorus content at
50ppm, again has similar copper purity to ETP, and only
about 2% lower conductivity."
"Other methods of oxygen removal include carbon reduction,
which avoids adding impurities."
As for the various grades:
"Oxygen Free copper is produced in several grades:
BS C103, Cu-OF and C110, Cu-OFE are melted and cast in
an oxygen free atmosphere to give very low oxygen level,
typically under 2ppm. For use in vacuum seals, e.g in
glass vacuum tubes, the C110 grade needs to be oxidised
on its surface at high temperature to gives good adhesion,
but even small amounts of phosphorus can reduce the adhesion,
so the level is kept below 3ppm."
"Cu-OF has conductivity almost identical to ETP, but Cu-OFE
is about 1.5% better. OFHC (a registered trade-mark) appears
to be similar to Cu-OFE. HC means 'high conductivity' while
OFE means 'oxygen free electronic grade'. Copper purity is
typically 99.997% for both."
A more concrete understanding of how such copper is made
can be derived from this pdf file from the site of the
Rautomead International Company in Britain, which makes
several machines for drawing continuous copper wire rods.
The machines are listed on this page:
http://www.rautomead.co.uk/products/copperwirerod.htm
The specific pdf file I'm referring to is for the
RS1050 Continuous Casting Machine, and is available here:
http://www.rautomead.co.uk/products/pdf/RS1050%20v1.pdf
It is also viewable in html in Google's cache, here:
http://216.239.53.104/search?q=cache:893kzn_XVsUJ:www.rautomead.co.uk/products/pdf/RS1050%2520v1.pdf+%22Oxygen+free+high+conductivity+copper%22+made&hl=en&lr=lang_en&ie=UTF-8
In reading it over, you can see that this machine uses
carbon reduction, which was mentioned above, in conjunction
with an atmosphere of inert gases, which precludes the
presence of oxygen.
The oxygen content of the resulting product is typically
less than 5ppm and no more than 10ppm.
A nominal breakdown of the composition and conductivity of
the various copper alloys is available on the Key-To-Metals
site, here:
http://www.key-to-metals.com/Article79.htm
As noted on the first site, OFHC is a registered trademark of
AMAX, Inc, also known as American Metals Climax, Inc., as
noted in this pdf file from the Freedom of Information Act
site:
http://foia.state.gov/masterdocs/05fah03/TAG0300.pdf
and viewable in Google's cache here:
http://216.239.53.104/search?q=cache:1N_R9kVPA10J:foia.state.gov/masterdocs/05fah03/TAG0300.pdf+%22American+Metals+Climax,+Inc&hl=en&lr=lang_en&ie=UTF-8
A pdf about NOR-CAL products, which asserts this trademark
ownership, is available on the Dutch DeMaCo site, here:
http://www.demaco.nl/images/upload/NorCal%20the%20company.pdf
There is no cache available for this document.
I believe that covers all the bases of your inquiry.
Please do not rate this answer until you are satisfied that
the answer cannot be improved upon by way of a dialog
established through the "Request for Clarification" process.
A user's guide on this topic is on skermit-ga's site, here:
http://www.christopherwu.net/google_answers/answer_guide.html#how_clarify
sublime1-ga
Additional information can be gleaned from further exploration
of the links provided above, as well as those resulting from the
Google searches, outlined below.
Searches done, via Google:
"Oxygen free high conductivity copper" made
://www.google.com/search?q=%22Oxygen+free+high+conductivity+copper%22+made
"OFHC is a registered trademark of"
://www.google.com/search?q=%22OFHC+is+a+registered+trademark+of%22
"American Metals Climax, Inc"
://www.google.com/search?q=%22American+Metals+Climax%2C+Inc%22 |