Special Materials

Mary Tang mtang at stanford.edu
Mon Dec 1 22:53:52 PST 2008


HI Mike and Senyo --

Much better.  However, it looks like it might be ethylene diamine 
based.  Better than cyanide salts, but still not the best.  First off, 
it stains benches terribly.  Second, we've banned EDP from the lab 
(ethylene diamine/pyrocatechol mix for etching silicon) because of 
safety concerns (same thing as cyanide salts -- OK if you have a 
dedicated setup with engineering controls, but not really OK to heat at 
our manual benches, since NH3 gas can be generated under a broad range 
of conditions.)  There's not a whole lot of info in the MSDS (is it 
really ethylene diamine and what's the rough concentration?) and I don't 
know what your protocol is (is the solution heated?  Do you need a power 
supply?  A quick Google search suggests to me this EDA is used for 
electroless plating of gold.)

What I'd really like to see is a clear, documented protocol for gold 
electroplating at the wbgaas bench -- everything from the administrative 
controls (like, maybe reserving the whole bench and blocking off with 
hazard tape when you're plating, or posting signs or sending out email 
notifications or whatever) to engineering controls (e.g. limited 
volumes, storing the power supply away from the bench) and as much info 
as possible about the chemical composition and the chemical reaction and 
byproducts. 

By the way, it seems that most gold electroplating solutions are 
incompatible with oxidizers and acids.  So for storage...  this could be 
stored in the personal chemicals storage in the chemicals passthrough 
(although there are oxidizers there, personal chemicals are separated by 
secondary containment) or in the Flammables cabinet area (there are no 
incompatibles in that area.)  We'll find a spot once you have the 
chemical (and a protocol that Uli and Jim H are happy with.)

Mary

Mike Wiemer wrote:
> Hi Mary & Specmat,
>
> Senyo and I are working together on this. 
>
> 1.) How about if we switch the chemical to the non-cyanide based one?
> Everything else would be the same (see Senyo's specmat request below). I
> have attached the new MSDS for the non-cyanide chemical.
>
> 2.) Where would we store the chemical? I would be a 1 gal jug....
>
> Best,
>
> -Mike
>
>
>
> -----Original Message-----
> From: Mary Tang [mailto:mtang at stanford.edu] 
> Sent: Tuesday, November 25, 2008 3:08 PM
> To: Senyo Dogbe
> Cc: specmat at snf.stanford.edu; uli at snf.stanford.edu;
> mwiemer at snf.stanford.edu
> Subject: Re: Special Materials
>
> 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
>>  
>>  
>>  
>>  
>>     
>
>
>   




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