Brian,
I believe Methylene Chloride and DCM are on the list of materials outlawed
by Montreal Protocol as Ozone depleting solvents.
Edward
Edward Szpruch
Eltek Ltd
P.O.Box 159 ; 49101 Petah Tikva Israel
Tel ++972 3 9395050 , Fax ++972 3 9309581
e-mail [log in to unmask]
> -----Original Message-----
> From: Brian Ellis [SMTP:[log in to unmask]]
> Sent: ד אוקטובר 30 2002 9:53
> To: [log in to unmask]
> Subject: Re: [TN] Acetone Test for Solder Mask
>
> Don
>
> Methylene chloride or dichloromethane (DCM) may be LISTED as a
> carcinogen by some idiotic organisations but large scale toxicological
> and epidemiological tests with cohort groups totalling over 10,000
> persons who have been industrially exposed to PROVE that it is NOT
> carcinogenic to humans. This gross error was brought about because
> testing on rodents did show slight carcinogenicity at very high exposure
> levels but these rodents have a metabolic path that simply is not
> present in humans. The European Centre for Toxicology and Ecotoxicology
> (ECETOC) have published very serious studies on all the available data
> for DCM, TCE and PCE, written and peer reviewed by the best brains in
> the business. My interpretation of one of their findings is: if every
> single adult in the USA were exposed to DCM at 50 ppm for 8 hours/day, 5
> days/week between the ages of 20 and 65, there would (statistically) be
> 1 death due to DCM-related cancer up to the age of 85 every 200 years. I
> can quote many references to support this, if required. I can also quote
> more detailed facts and figures. I should mention that I have no
> interest in chlorinated solvents; in fact, I avoid them where possible,
> but it isn't always possible, because they are very useful molecules.
>
> This is not to say that DCM is not toxic. It is. Unfortunately, even if
> it does not cause cancer, it has an insidious effect on the human body
> at high exposure levels, with a threshold starting about 250 ppm. One of
> the metabolic breakdown products of DCM is carbon monoxide. This
> combines with the haemoglobin in the blood to form carboxyhaemoglobin
> (COHb). This is relatively persistent (several weeks) and COHb molecules
> are Hb molecules that cannot transport oxygen to the various organs.
> This can cause suffocation. It accumulates to an equilibrium level, in
> relation to the exposure level, over a matter of weeks. I know of no
> case resulting in death, but there are cases on record where the
> patients had to be hospitalised for a few weeks with combined oxygen
> therapy and blood exchange. Of course, these patients had been exposed
> to really massive, consistent, levels.
>
> All halogenated solvents must be treated with respect with minimal
> exposure levels, but it really gets my back up when political bodies who
> should know better make sweeping statements resulting in unnecessary
> restrictions and which cannot be scientifically supported:
> carcinogenicity of DCM is only one, have a thought about lead in solder
> for another.
>
> Brian
>
> Don Vischulis wrote:
> > I believe that the methylene chloride cure test was originally used for
> one
> > and two part screened masks. It was later modified for use with dry
> film
> > masks. I don't know the origin of the "acetone test", but my guess is
> that
> > somebody decided to use acetone instead of methylene chloride because
> > methylene chloride is listed as a carcinogen. I know that methylene
> > chloride is not acceptable for use with UV cure and several LPI masks.
> >
> > Anyone else?
> >
> > Don Vischulis
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
> > Sent: Tuesday, October 29, 2002 1:19 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Acetone Test for Solder Mask
> >
> >
> > Carrie,
> > I don't know about acetone, but the test you are talking about sounds
> like
> > IPC-TM-650 Test Methods Manual,number 2.3.23, "Cure (Permanency)
> Thermally
> > Cured Solder Mask", where they talk about using methylene chloride.
> >
> > Perhaps your test is out of the old, what was it, SM840? Anyone else?
> >
> > regards,
> > Bev Christian
> > Research in Motion
> >
> > -----Original Message-----
> > From: Morse, Carrie [mailto:[log in to unmask]]
> > Sent: October 29, 2002 2:08 PM
> > To: [log in to unmask]
> > Subject: [TN] Acetone Test for Solder Mask
> >
> >
> > We are currently doing an "Acetone Test" on our incoming PWB's to test
> for
> > solder mask cure.
> > Our test entails saturating a swab with acetone and rubbing it on the
> mask.
> >
> > Does anyone know where this test comes from? Is it a documented IPC
> test?
> >
> > Also, if we do see any residue (i.e.: green or blue discoloration on
> the
> > swab), what does this
> > tell us and how much is enough to deem the test "failed"?
> >
> > -Carrie
> >
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