Bev,
I think you present an interesting, and frightening, argument. For your
example, my question would be - can the components of mold compound be
"disjointed" mechanically. Specifically, is it possible to mechanically
separate the filler from the resin by cryogenically grinding (or some other
mechanical means)? To take this further, is it then possible to "disjoint"
the other components in the compounds such as flame retardants, etc? I am
not a polymer chemist, but I wouldn't be surprised to find that a creative
person would be able to find ways to mechanically separate a variety of
items that we may presently believe to be homogeneous. If this is true,
then the question becomes - at what level does the analysis end? There is a
point in which the contaminants are further and further disjointed and
isolated from the starting mold compound, which means that the % content of
the contaminant is becoming more and more significant. If you are able to
disjoint down to the elemental level, then the contaminant becomes 100% of
the sample!
Mike
-----Original Message-----
From: Bev Christian [mailto:[log in to unmask]]
Sent: Thursday, August 26, 2004 8:27 AM
To: [log in to unmask]
Subject: Re: [LF] Antw: Re: [LF] INTERPRETATION OF EU DIRECTIVES, ETC.
Dave,
There are people whose native tongue is English on the EU TAC, so as much as
I WISH it was a translation problem, I am pretty sure it is not.
Unless the above-mentioned group has absolutely and totally taken leave of
their senses, "homogeneous materials" can also mean compounds and can even
mean mixtures. Now I admit I am on shakier ground on the latter. The latter
depends of course on the granularity one goes to define the size of one unit
of volume measure. If one assumes a cubic millimeter as your unit of volume
measure and, for example, if one had a component overmold plastic with
finely divided, evenly dispersed alumina (Al2O3) in it, I am quite confident
(but never completely sure :) ) that if the TAC were for some bizarre
reason interested in Al2O3, then they would accept a ppm concentration of
the alumina based on the weight of the overmold, not the alumina itself.
It will be interesting to see what responses I get to this!
regards,
Bev Christian
RIM
-----Original Message-----
From: MA/NY DDave [mailto:[log in to unmask]]
Sent: August 26, 2004 3:13 AM
To: [log in to unmask]
Subject: Re: [LF] Antw: Re: [LF] INTERPRETATION OF EU DIRECTIVES, ETC.
Hi IPC LF Listservers, Gaby, Bev and Guenter,
Wow this note tread moved on over to simple science to solve a .1% by
weight bulk property with a cotton swab and a dab of whatever like WD40, or
maybe a Lowenbrau. WOW!!! I guess science is a challenge for most people.
How about spit as an indicator after one eats let's say garlic, onions, or -
--.
Sorry for being not nice, SO back I go to Bev's original question.
Bev and Others, back awhile ago when I read On List about this procedure of
I can cut, I can grind, and I can do all these other things to get to the
true homogeneous material I thought this was totally SCREWY, and BLOODY.
Something had to be wrong with the normal English translation of the
process that was listed and the way my brain translated this process. The
word "Grinding" told me something was amiss in the translation.
On top of this I remembered another tread that Tin's Kay started awhile
before about "Homogeneous Material" where she asked us our interpretation.
My guess was that homogeneous material means what we think it should mean
yet at the single element level that when put together creates the entire
assembly. A lead with all it's metallurgy, the solder, the printed circuit
board without components, etc
As I believe Guenther pointed out this is a time consuming analysis, and
time is better spent making sure that BY-DESIGN all the suppliers have
removed Lead from from each element.
Yours in Engineering, Dave
Y i Engr, MA/NY DDave
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