Good job Ray!
You did you Homework A+
Louis T. Dallara
Product Design Information (PDI) Group- Dept. 52R143000
LUCENT TECHNOLOGIES - MICROELECTRONICS GROUP
Optoelectronics Business Unit
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> ----------
> From: Ray Humphrey[SMTP:[log in to unmask]]
> Reply To: DesignerCouncil E-Mail Forum.;Ray Humphrey
> Sent: Monday, December 14, 1998 6:43 PM
> To: [log in to unmask]
> Subject: Re: [DC] Plated Thru pads
>
> IPC-D-782 says, "Nonfunctional lands should be included on internal layers
> for all plated-through holes. Nonfunctional lands need not be used where
> electrical clearance requirements do not permit, such as ground planes,
> voltage planes and thermal planes."
>
> Norman Einarson's Bare Board PWB Design Manual says, "Non-functional lands
> should be removed from inner layers, prior to the artworks being released
> for production. These are the lands on inner layers where no circuit will
> be connected to any hole." Further, its says, "During the lamination
> process, the epoxy in the pre-preg material will flow to the outer edges
> of
> the board. This may cause the lands with no traces attached to float when
> the epoxy is flowing prior to cure."
>
> Summary - Talk to your own PCB vendor.
>
> -----Original Message-----
> From: KELLY M SCHRIVER <[log in to unmask]>
> To: [log in to unmask] <[log in to unmask]>
> Date: Monday, December 14, 1998 2:48 PM
> Subject: Re: [DC] Plated Thru pads
>
>
> >Scott -
> >
> >I think most of us are leaving all of the unused pads in place on plated
> thru
> >holes and vias, unless removal is necessary to increase routing density.
> >Leaving the pad stack intact adds just a bit of uniformity and stability
> to
> >the hole. With part of the pads gone, Z axis attachment of the barrel
> can
> >vary considerably. This gets more important as the hole aspect ratio
> >increases.
> >
> >ITRI recently completed some testing dealing with allowable
> misregistration,
> >which strongly supports the stability theory. This testing suggests that
> a
> >trace connecting directly to a barrel will survive IF a pad is present,
> even
> >though severely misregistered (giving a breakout condition).
> >
> >Regards - Kelly
> >
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