Special Materials

Mary Tang mtang at stanford.edu
Tue Nov 25 15:08:27 PST 2008


Hi Senyo --

Thanks for the request.  I'm afraid, though, that you would have to 
justify using cyanide-based solution in our lab.  Although this has been 
used in the distant past, it was used at a wet bench that was dedicated 
for gold electroplating.  We no longer have this set up -- and manual 
handling of these kinds of chemicals poses greater risks.  So, if this 
were to be allowed, we'd have to have very strict procedures and rules 
about use of this class of chemicals.

The reason is that these cyanide based solutions are highly toxic.  
Cyanide can be easily absorbed through the skin upon contact.  Free 
cyanide vapors are extremely toxic and can be easily generated when the 
solution comes in contact with oxidizing acids, as might occur when 
using at one of the shared stations.  In fact, when medical 
professionals respond to cyanide poisonings, they will not work on a 
victim until all clothing and anything the person has come into contact 
is removed.  And my concern is personal -- similar cyanide solutions are 
often used in synthetic chemistry -- just down the hall from the lab 
where I did my graduate work, a post-doc doing synthetic chemistry died 
from cyanide poisoning.

I understand that cyanide based solutions are preferred for some 
applications, especially electronics, but that much safer solutions, 
such as sulfide based ones are also available.  I'd recommend doing some 
investigation into other electroplating solutions to determine which 
would meet your needs.  If your requirements are more stringent, then 
I'd suggest sending your devices out for gold electroplating -- there 
are several local services which specialize in electronics 
applications.  Finally, I'm copying Mike Wiemer on this -- Mike is also 
interested in a non-cyanide-based gold electroplating solution for quick 
turnaround processing.  Maybe you two could share notes and work with 
Uli and Jim H (who are responsible for the wbgaas station) on 
establishing a procedure for the lab.

Thanks,

Mary

Senyo Dogbe wrote:
> Dear Sir/Madam,
> I would like to seek permission to use a non-standard chemical for 
> future work in device processing at SNF.
> The information below and the attached MSDS provide more information 
> about the Chemical.
>  
> Chemical Name - Techni-Gold 434 HS  (for electroplating).
>  
> MSDS - Attached.
>  
> Equipment - GaAs wet bench.
>  
> Procedure - Beaker (labuser to provide own beaker) with leads attached 
> to DC regulated power supply. Beaker to be placed on hot plate at 50C. 
> Plating Chemical will be lightly stirred with a stir bar.
>  
> Power Supply -BK Precision DC regulated power supply. Model #1670A. 
> Max current for electroplating will be at 5mA ( a couple of volts  
> from DC power source required for this process).
>  
> Waste Disposal - Lab user intends to use waste collection bottle to 
> catch the rinse water so that waste water does not go into AWN system. 
> The used 434 chemical will be stored in a labelled waste bottle.
>  
> Thanks
>  
> Senyo
>  
>  
>  
>  


-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu




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