aqua regia processing in SNF...

Mary Tang mtang at stanford.edu
Mon Mar 12 09:31:38 PDT 2012


Hi Robert --

I'm afraid aqua regia may be your best bet for Pt and Pd, but there may 
very well be new mixtures out there and trust your search will uncover 
them.  And I'd forgotten that Berkeley looked at diluted aqua regia.  
Still, mixing in water may pose a challenge.  Though if your volumes are 
very small as done at Berkeley, it's no doubt manageable.  So, if you 
determine that you need aqua regia, I'd like to request that your 
procedure address the following concerns:

- Ensure there are no bystanders (minimize exposure to splattering and 
explosion risk)
- Secondary containment (the benchtop at wbgeneral is combustible 
polypro, something we plan to fix this later this year... Having worked 
as an undergrad in a lab where a sample ate its way through its 
container, the lab bench storage cabinet and through the ceiling of the 
lab underneath, I am paranoid - though, that particular sample was a 
magic acid, way more powerful than aqua regia)
- Waste - with dissolved heavy metals, the used acid should not be 
aspirated -- however, keeping it for disposal and allowing it to 
decompose is a bad idea.  Although as a rule, we don't treat waste, this 
might be an exception, so there should be a procedure for rendering it 
safe enough to store in a waste container for disposal by EH&S.

My main concern is making sure we keep tabs on who, when, and how aqua 
regia is used -- quite honestly, there are some labmembers who should 
probably not be trusted to do this process on their own.  So I would 
suggest working with Uli to come up with a way to help control its use.

M

On 3/12/2012 8:19 AM, Robert Huang wrote:
> Hi Mahnaz, Jim, and Mary,
>
> Thanks for your feedback, and we understand the concern with the aqua regia processing and that it is not currently approved for processing at SNF.  We will look into its use further as well as whether there is another more readily-available and hopefully safer alternative.  FYI, we are interested in using it to selectively etch metal layers like Pt and Pd.  The attached paper shows that it selectively etches these types of materials well.
>
> If we decide we do need to try the aqua regia etch, we will be sure to follow-up with the CCB on all the points requested.
>
> Regards,
>
> Robert Huang
> Director, Process and Device Technology
> QuSwami, Inc.
> 455 Mission Bay Blvd. South
> Building 3, Suite 125
> San Francisco, CA 94158
> W: (415) 834-9910
> M: (408) 854-0450
> F: (415) 834-9975
> Email: roberth at quswami.com
>
> **********************Privacy and Confidentiality Notice**********************
> The information contained in this communication is proprietary, confidential, copyright, trade secret of QuSwami, Inc. It is intended solely for the use of the individual or entity to whom it is addressed and others authorized to receive it. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution or taking any action in reliance to the contents of this information is strictly prohibited.
> ******************************************************************************
>
> -----Original Message-----
> From: Mary Tang [mailto:mtang at stanford.edu]
> Sent: Sunday, March 11, 2012 2:54 PM
> To: Mahnaz Mansourpour
> Cc: Jim McVittie; Robert Huang; Specmat at snf.stanford.edu; maurice stevens; Uli Thumser; John Bumgarner; Maurice Stevens
> Subject: Re: aqua regia processing in SNF...
>
> Hi all --
>
> Jim is absolutely right, this stuff needs to be respected.  The mixture creates a "superacid" whose pKa is more acidic than pure sulfuric acid.
> Aqua Regia was once used widely in the semiconductor industry (and just about any where else that chemical brute force was used), but has been phased out due to safety reasons.  It's also highly discouraged for use in university labs, because there are almost always safer alternatives for most of the applications for which it is generally used (for example, KI for etching gold.)
>
> Please refer to:
> http://www.aiha.org/insideaiha/volunteergroups/labHandScommittee/Pages/IncidentsExplosions.aspx
>
> Therefore, for the CCB, some homework (i.e., demonstration of due
> diligence) will be required.  Basically, we'd want to see:
>
> 1.  Your process flow showing how and why it would be used.
> 2.  An overview of possible alternatives to aqua regia and why or why not they would work for your process.
> 3.  A detailed procedure on how this process would be done, especially
> safety measures to be taken.   This should include the volumes and what
> order your chemicals are to be mixed and how you will dispose of waste, how the area will be isolated from other labmembers, a description of the labware you will use, how long your process is, secondary containment for your chemical vessels.  And I'm with Mahnaz, why the water?  I'm no expert, but it strikes me as being rather dangerous to
> add water...   Make sure to read the MSDS -- it's not the same as HCl
> and Nitric -- it is air reactive, strongly oxidizing, water reactive, self-heats, and decomposes into toxic gases, according to a couple I've just pulled up...
>
> I honestly have never worked with aqua regia, so personally can't
> contribute much on its safe use.   If you want to use it, we'd have to
> have a good rationale and clearly defined procedures for its use.  I expect that we would draw tight boundaries around how, when, and who can use it in the lab.
>
> Mary
>
> On 3/11/2012 9:14 AM, Mahnaz Mansourpour wrote:
>> Hi all,
>>
>> Jim thanks for information.
>> Just to be sure, specmat, have not okay the process yet.
>> Robert , please attend the next CCB meeting, Thursday at 2:30.
>> i hope I have the time correct?
>>
>> mahnaz
>> On 3/10/2012 12:30 PM, Jim McVittie wrote:
>>> Robert,
>>>
>>> Be very careful in using aqua regia. It can suddenly "spitted" acid
>>> out of a beaker. Mixing HCl and NHO3 forms a new stronger acid.  As a
>>> gradate student, I use to mix a gal of it up at a time for doing
>>> super cleaning of quartz ware. Over the years better methods were
>>> found for cleaning quartz. It was also used for cleaning Si before
>>> the advent of the RCA clean.   Jim
>>>
>>> ----- Original Message -----
>>> From: "Mahnaz Mansourpour"<mahnaz at stanford.edu>
>>> To: "Robert Huang"<roberth at quswami.com>,
>>> "Mahnaz"<mahnaz at stanford.edu>, Specmat at snf.stanford.edu, "maurice
>>> stevens"<maurice at stanford.edu>, "Uli Thumser"<uli at snf.stanford.edu>
>>> Sent: Friday, March 9, 2012 2:08:04 PM
>>> Subject: Re: aqua regia processing in SNF...
>>>
>>>
>>> Hi Robert,
>>>
>>> Mixing HCL and NHO3 is ok but why mix it with water?
>>> I am not sure how will react?
>>> Please give me more information.
>>>
>>> mahnaz
>>> On 3/9/2012 11:16 AM, Robert Huang wrote:
>>>
>>>
>>>
>>>
>>> Hi Mahnaz,
>>>
>>>
>>>
>>> So of course HCl and HNO3 are already approved chemicals in SNF. I
>>> assume it is then OK to mix them up in an aqua regia solution (3
>>> parts HCL, 1 part nitric, and 2 parts water) for use at wbgeneral
>>> (our intent is at room temperature) as long as we follow the usual
>>> guidelines including proper labeling, correct?
>>>
>>>
>>>
>>> Regards,
>>>
>>>
>>>
>>>
>>> Robert Huang
>>>
>>> Director, Process and Device Technology
>>>
>>> QuSwami, Inc.
>>>
>>> 455 Mission Bay Blvd. South
>>>
>>> Building 3, Suite 125
>>>
>>> San Francisco, CA 94158
>>>
>>> W: (415) 834-9910
>>>
>>> M: (408) 854-0450
>>>
>>> F: (415) 834-9975
>>>
>>> Email: roberth at quswami.com
>>>
>>>
>>>
>>> **********************Privacy and Confidentiality
>>> Notice**********************
>>>
>>> The information contained in this communication is proprietary,
>>> confidential, copyright, trade secret of QuSwami, Inc. It is intended
>>> solely for the use of the individual or entity to whom it is
>>> addressed and others authorized to receive it. If you are not the
>>> intended recipient, you are hereby notified that any disclosure,
>>> copying, distribution or taking any action in reliance to the
>>> contents of this information is strictly prohibited.
>>>
>>> *********************************************************************
>>> *********
>>>
>>>
>>>
>>>
>>>
>>>
>>> From: Robert Huang
>>> Sent: Thursday, March 08, 2012 1:05 PM
>>> To: 'Mahnaz Mansourpour'
>>> Subject: aqua regia processing in SNF...
>>>
>>>
>>>
>>> Hi Mahnaz,
>>>
>>>
>>>
>>> Is aqua regia (combination of HCl and HNO3) already an approved
>>> chemical in SNF? If so, what are the procedures including where it
>>> can be used?
>>>
>>>
>>>
>>> Regards,
>>>
>>>
>>>
>>> Robert Huang
>>>
>>> Director, Process and Device Technology
>>>
>>> QuSwami, Inc.
>>>
>>> 455 Mission Bay Blvd. South
>>>
>>> Building 3, Suite 125
>>>
>>> San Francisco, CA 94158
>>>
>>> W: (415) 834-9910
>>>
>>> M: (408) 854-0450
>>>
>>> F: (415) 834-9975
>>>
>>> Email: roberth at quswami.com
>>>
>>>
>>>
>>> **********************Privacy and Confidentiality
>>> Notice**********************
>>>
>>> The information contained in this communication is proprietary,
>>> confidential, copyright, trade secret of QuSwami, Inc. It is intended
>>> solely for the use of the individual or entity to whom it is
>>> addressed and others authorized to receive it. If you are not the
>>> intended recipient, you are hereby notified that any disclosure,
>>> copying, distribution or taking any action in reliance to the
>>> contents of this information is strictly prohibited.
>>>
>>> *********************************************************************
>>> *********
>>>
>>>




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