I second Dewey's statement. I also used in my earlier years before we took
MSDS's too seriously and we all thought we were bulletproof. I remember
when holding my breath was a 'safe' practice for removing hydraulic fluid
from my skin with trichloroethylene. THF is really bad stuff. Below are
some excerpts from the JT Baker web site MSDS for THF.
IC companies have been asking about the extended list hazardous substances,
beyond the "RoHS 6", so I have had to look into a lot of nasty chemicals
recently, particularly the "Dirty Dozen" Persistent Organic Pollutants
(POPs) listed in the Stockholm Convention.
Furans (dibenzofuran - also known as Diphenylene Oxide, and
chlorodibenzofuran are on the Dirty Dozen list of most toxic POPs. I know
THF is a totally different compound, but it does contain the word 'Furan' in
the name, and THF is also known as Diethylene Oxide, and for a non-organic
chemist, this is close enough to "diphenylene oxide", AKA dibenzofuran, for
me to want to avoid THF.
http://www.jtbaker.com/msds/englishhtml/t1222.htm
1. Product Identification
Synonyms: Diethylene oxide, oxacyclopentane; THF; tetrahydrofuran and
stabilizer; 1,4-Epoxybutane; Butylene Oxide; Cyclotetramethylene Oxide;
Furan, tetrahydro
CAS No.: 109-99-9
Molecular Weight: 72.11
Chemical Formula: CH2CH2CH2CH2O
Product Codes:
J.T. Baker: 9439, 9440, 9441, 9442, 9446, 9447, 9449, 9450, V530
Mallinckrodt: 2858, 8497, 8498, 8499, V558
Emergency Overview
--------------------------
DANGER! EXTREMELY FLAMMABLE LIQUID AND VAPOR. VAPOR MAY CAUSE FLASH FIRE.
MAY FORM EXPLOSIVE PEROXIDES. HARMFUL IF SWALLOWED OR INHALED. CAUSES
IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS CENTRAL NERVOUS
SYSTEM.
Carcinogenicity:
Under the National Toxcology Program (NTP), the U.S. Public Health Service
completed a 2-year (lifetime) inhalation study in rats and mice on
Tetrahydrofuran (THF) which suggests that THF is a carcinogen in laboratory
animals. There is no data linking THF exposure to cancer in humans. The data
shows carcinogenic activity in the liver and kidneys of laboratory animals.
Potential Health Effects
----------------------------------
Inhalation:
Causes irritation to the respiratory tract. Symptoms may include coughing,
shortness of breath. THF is an anesthetic agent in high concentrations.
Overexposure may cause dizziness, headache, nausea and possible fluid in the
lungs. May cause liver, kidney or lung injury.
Ingestion:
Causes irritation to the gastrointestinal tract. Symptoms may include
nausea, vomiting and diarrhea. May cause sore throat and abdominal pain. May
cause liver or kidney injury.
Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain.
Eye Contact:
Causes irritation, redness, and pain. Contact may cause permanent eye
damage.
Chronic Exposure:
Repeated or high exposures may cause kidney or liver damage; may affect the
lungs. Repeated skin exposure can cause dryness, cracking of skin and rash.
Aggravation of Pre-existing Conditions:
Persons with pre-existing skin disorders or eye problems or impaired liver
or kidney function may be more susceptible to the effects of the substance.
Best regards,
Leo
Leo M. Higgins III, Ph.D.
Vice President, Technical Support Operations
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas 78704
office phone 512-383-4593
mobile 512-423-2002
[log in to unmask]
www.asat.com
The information contained in this electronic message is CUSTOMER/SUPPLIER
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Whittaker, Dewey
(AZ75)
Sent: Thursday, April 20, 2006 4:22 PM
To: [log in to unmask]
Subject: Re: [TN] Parylene Coating Removal...
I've used it and made it. Be very , very, very afraid. Do Not Use It.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, April 20, 2006 2:18 PM
To: [log in to unmask]
Subject: [TN] Parylene Coating Removal...
Hi All!
I've always thought that when it comes to removing parylene coating,
about the only way you can remove it is with some sort of mechanical
means, i.e.; microabrasion, or scraping. Burning through it with a
soldering iron when trying to do rework it is very, very
difficult...I've tried it...it doesn't work well at all.
I was just told that a chemical that I haven't heard of before might
work, it's called THF, or Tetrahydrofuran. I was told that it won't
dissolve the coating, but will cause it to lift from the PCB where it
can be brushed away. Have any of you ever heard of this stuff? I'm not a
chemist, and I'm not about to use it until I learn more about it.
The issue that I have is with a little tiny assembly that has been built
and parylene coated with some bad programmable hall effect switches
installed. The board is so small, and there are other components
installed really close to where the coating has to be removed. I'm
afraid of getting them microblasted because I'm afraid of damaging the
other components. See the assembly at:
http://stevezeva.homestead.com/files/8001_assy_backside.JPG ...the small
components are 0402's, so that gives you a visual scale of how big the
assembly is...
I've got the information in to a company that I found that does laser
ablation to remove coatings to give us a quote, so I'm waiting on that.
But if that turns out to be really expensive, I was contemplating using
the THF as plan "B" (provided the stuff will work and it doesn't hurt
anything else on the assembly).
Kind regards,
-Steve Gregory-
Senior Production Engineer
OAI Electronics
East 12th Street
Tulsa, Oklahoma 74112
(918) 836-9077 Ext.-507
(918) 706-2779 CELL
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