Now that is interesting and very valuable information. I will follow this
very closely even from "outside" the round robin and other reliability
testing.

Thanks a bunch Werner,

Earl

----- Original Message -----
From: "Werner Engelmaier" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, September 06, 2002 1:17 PM
Subject: Re: [TN] IPC-TM-650-2.6.8, Thermal stress, Plated Through Holes


> Hi Earl,
> ILS was previously referred to 'post-separation.'
> Actually, the forces are not exerted diagonally to the trace/pad to
conductor
> interface, but radially relative to the PTH barrel. This is the result of
the
> PTH barrel experiencing the same compression deformation as a submarine on
> diving; except, of course, that a submarine has its reinforcement ribs on
the
> inside and the PTH barrel on the outside [that's the functional and
> non-functional lands]. The traces resist the compressive movement of the
> barrel and failure can occur at the weakest of 3 links [ plating/flash
> interface, flash/foil interface, foil]. When the compressive deformation
is
> plastic for the copper barrel, hole separation occurs as the resin returns
to
> its former position on cooling.
>
> Werner
>
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