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October 1998

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 14 Oct 1998 16:46:58 -0400
Content-Type:
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Scott,
You wrote:
> I have a customer who is concerned about Ionic contamination due to
> bromines/bromides. I have explained to the customer that the flame
> retardant in FR-4 material is based on bromine. Also, the flux that we use
> for the HAL is Hydrobromic Acid based, this is used instead of
> Hydrochloric
> Acid based flux to cut down on the chloride contamination
>
Here is some more stuff for you.  The fire retardants are polybrominated
diphenyl ethers (PBDEs).  These are organic materials, which mean that the
bromine is not present in ionic form (not present as Br-), but is covalently
bonded (share electrons) to the carbon backbone of the molecule.  So
theoretically these compounds should provide no ionic contamination at all.
However, I am not aware of what purity level these materials are when
shipped to epoxy formulators.  The other problem is that carbon-bromine
bonds are not the strongest in the world and many are susceptible to
dissociation, especially in the presence of light.  Heat doesn't help
either, but this also varies from compound to compound.  And who knows how
other materials in the circuit board may or may not act as catalysts.  Some
of this bond breakage may result in the formation of free bromide ions
rather than neutral radicals.

For environmental reasons there is a controversy raging over PBDEs, so there
is a search on for alternatives.  One of our competitors has come out with
one based on phosphate.  I think the phosphate is bound in little pouches
like on a scratch and sniff card so there is not a problem with pH, but I'm
not entirely sure on that.  The boards can only be bought from one or two
vendors so far and are more expensive than regular FR-4.  I know of no other
alternatives this far along.

regards,
Bev Christian
Nortel

> ----------
> From:         Ozark Circuits[SMTP:[log in to unmask]]
> Sent:         Monday, October 12, 1998 11:03 AM
> To:   [log in to unmask]
> Subject:      [TN] Ionic Contamination due to No-Clean Fluxes
>
> I have a customer who is concerned about Ionic contamination due to
> bromines/bromides. I have explained to the customer that the flame
> retardant in FR-4 material is based on bromine. Also, the flux that we use
> for the HAL is Hydrobromic Acid based, this is used instead of
> Hydrochloric
> Acid based flux to cut down on the chloride contamination.
>
> If anyone has information concerning this subject, I would appreciate any
> and all information. I can be contacted at:
>
> Scott Foley
> Environmental & Process Manager
> Ozark Circuits, Inc.
> 933 W. Chase
> Springfield, Missouri 65803
> Phone: 417-864-5004
> Fax:   417-864-4072
> email: [log in to unmask]
>
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