Rudy

Thank you for your input, since it is brings the discussion to a clearer
level.  I did not want to get into this topic since I haven't studied
polyimide.  But as a materials scientist, I have to add my two cents:
Polarity is part of the issue.  Polymers are pictured like strands of
spaghetti.  Some are long, others are coiled, etc.  So, molecular structure
is very important as well (think of a perfect compact solid material in
comparison to one with holes in it).  The openness of sites along the
molecular chain to fit a molecule too.

In general, I just accept that someone else has studied it and it is a fact
that must be lived with.  If you want to challenge that concept, then spend
a year or so working with it.

Carey

-----Original Message-----
From: <Rudy Sedlak> <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Monday, February 28, 2000 7:32 AM
Subject: Re: [TN] Polyimide--More than you wanted to know


>With the caveat that free advice is often not worth what you pay for it....
>
>Water is a polar solvent, meaning it has a charge, the Oxygen keeps a
slight
>excess of electrons away from the Hydrogen, thus maintaining a charge.
>
>This is not the case with carbon-hydrogen type solvents like say, kerosene,
>or motor oil.  It is essentially non-polar, or charge free.
>
>Polyimide is more polar than FR-4, containing Nitrogen (which tends to act
>like Oxygen, and maintain a charge) and this attracts the water.  Polyimide
>is more "polar", or charged, and the rule in chemistry is "like dissolves
>like", so Polyimide loves water more than its uncharged cousin FR-4.
>
>In Chemistry...
>
>Rudy Sedlak
>RD Chemical Company
>
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