Al is an expected component of FR-4 since E-glass is about 15% Al2O3.
Timothy Reeves
ECD Circuit Board Division
13626 South Freeman Road
Mulino, OR 97042
[log in to unmask]
(503) 829-9108 (800) 228-8198 FAX (503) 829-5482
> ----------
> From: McFaddin, Wade
> Sent: Friday, February 4, 2000 6:01 AM
> Subject: Re: electrical shorts in RCC (resin coated copper) build up
> layer
>
> Hi Thomas,
>
> I can't comment on you root problem with the resin coated copper shorts,
> but
>
> I did have a quick thought on the SEM/EDX results you mentioned. The
> bromine
> signal (peak) is most likely coming from the flame retardants used in the
> laminate.
> The aluminum signal (peak) that you are seeing is also coming from the
> bromine.
> Bromine and aluminum signals overlap at 1.48keV on the EDX spectrum and
> cannot be separated. However, bromine has additional lines (peaks) at 11.9
> keV
> that can be identified. So if bromine is present there is no easy way to
> determine
> if aluminum is present by EDX. You would need to use another analytical
> technique
> such as WDX, but that's another story.
>
> Hope this helps,
> Wade McFaddin
> NEXTEK Inc.
>
> > -----Original Message-----
> > From: Thomi [SMTP:[log in to unmask]]
> > Sent: Thursday, February 03, 2000 7:46 PM
> > To: [log in to unmask]
> > Subject: [TN] electrical shorts in RCC (resin coated copper) build
> up
> > layer
> >
> > Dear Technetters,
> >
> > has anyone come across a root cause for electric shorts between
> > neighboring copper lines of different potential within a layer laminated
> > with RCC (resin coated copper)? We have carefully ground away layers 1+2
> > from one side, and layer 4 from the other, to find a (ca.) 1 micrometer
> > diameter filament connecting two neighboring lines in layer 3. Cross
> > sectioning this further, we could analyse this filament by using SEM/EDX
> > and found copper. The surrounding resin shows peaks of Bromium (probably
> > from flame retardants) and Aluminum (??Al2O3 filler material??). The
> > electric short was not detected during bare board testing, but occured
> > within one week of functional testing of the full assembly in an
> > environmental chamber operating at 120°C (I wouldn't believe it!).
> >
> > Is there a certain resin condition under which copper migration is
> > enhanced within the RCC-resin (however close to the interface with the
> > core to which the RCC is laminated)? There is a recommendation to ensure
> > driving/baking out humidity from the multilayer, which makes me somewhat
> > suspicious, but I don't know enough about the constituents (resin,
> > hardener, flame retardant, maybe filler material) to try and explain
> what
> > happens electrochemically.
> >
> > Best regards,
> >
> > Thomas Ahrens, Memellandstr. 8, D-24598 Boostedt
> > Tel. ++(49) (0) 4393 97769 e-mail [log in to unmask]
> > <mailto:[log in to unmask]>
> > Bitte beachten - please note:
> > - Mails groesser als 2 MB werden nicht angenommen
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>
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