Paul, 
did use Laser to isolate a device on FR4 before (failure analysis).  Ran
into problem with safty and health concern.  The equipment have to install
special vent to ensure all the fumes were collected and vent properly (as
you can imaging, the fume is localized, but concentrated.)...Only tried
once, I wouldn't recommended.
                                       jk
At 09:45 AM 2/10/00 +0200, you wrote:
>Paul
>
>Am not a toxicologist, but I understand that the organobromides are loosely
crosslinked
>into the epoxy and that they function by releasing hydrogen bromide and
some other
>nasties on heating beyond about 350°C. This HBr is the actual extinguishing
agent. HBr
>is decidedly very toxic and corrosive. Most organobromides are more or less
toxic and
>environmentally unfriendly. Some of the other released compounds may also be
>ozone-depleting. However the quantities are relatively small.
>
>FR-4 without the organobromides is called G-10 and supports continuous
combustion in
>air. It also produces toxic vapours, although less so and, of course, no
>organobromides.
>
>Brian
>
>Paul Klasek wrote:
>
>> Could you fellows enlighten me on toxicity of this additives please ,
>> and what goes into "standard" FR4 ?
>>
>> Debate circulates about what harm can charring board do in a ventilator :
>> With or without retardant :
>> How far is the standard glass laminate prone to ignition/combustion/char and
>>
>> what would be the effects of toxins generated ?
>>
>> Thanks a lot
>>
>> Paul Klasek
>> http://www.resmed.com
>>
>> ##############################################################
>> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>> ##############################################################
>> To subscribe/unsubscribe, send a message to [log in to unmask] with
following text in
>> the body:
>> To subscribe:   SUBSCRIBE TECHNET <your full name>
>> To unsubscribe:   SIGNOFF TECHNET
>> ##############################################################
>> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
>> information.
>> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
>> 847-509-9700 ext.5365
>> ##############################################################
>
>##############################################################
>TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>##############################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in
>the body:
>To subscribe:   SUBSCRIBE TECHNET <your full name>
>To unsubscribe:   SIGNOFF TECHNET
>##############################################################
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
>information.
>If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
>847-509-9700 ext.5365
>##############################################################
>

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################