Earl,
Certainly you're not saying that the hole wall thickness can
be taken into account when performing annular ring measurements????
While I agree that the hole wall may be part of
the annular ring, but only as it's point of termination.
In determining annular ring thickness I look at
the diagrams in IPC-A-600, section 3.3.1 Annular Ring-Internal Layers. The
diagram arrows identify beginning and end of the annular to be
measured???
Also, IPC-A-600, paragraph 2.10.2 Annular Ring-Measurement,
The first line reads "Annular Ring is the annular solderable area
between the edge of the drilled hole and the
edge of the land.
I read this to mean surface and not encroaching upon the hole
wall at all.
Of course this is only how I do this, and I've
never been known to be wrong ~guffaw~
Regards,
Franklin D Asbell
1 mil, technically, is not
breakout. Back in the good old days with H-P
(1970 something), their
specification clearly required a 1 mil annular ring
throughout the MLB
structure. This was reasoned based on minimum hole wall
plating. In other
words it was, and is, not possible to have breakout with
that much plating in
the hole. Something to consider along with all that
goes with it as minimum
ductility and plating quality, etc.
Earl Moon
----- Original Message
-----
From: Ken Patel <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, October
14, 1999 1:00 PM
Subject: [TN] Risk involved in accepting inner layer
misregistration
> What are the consequences of accepting board
with inner layer
> misregistration (90 degree break out)? This
misregistration occurred at 1
> mil micro-BGA location.
>
> We
have heard that: There are no reliability issues with breakout
from
inner
> layer via's and that the industry may be moving away from
this
requirement.
> Is it true? Currently, IPC-600 Class3 calls out for
.001" annular ring.
>
> re,
> ken patel
>
______________________________________________________
> Ken
Patel
Phone: (408) 490-6804
> 1708 McCarthy
Blvd.
Fax: (408) 490-6859
> Milpitas, CA
95035
Beeper: (888) 769-1808
>
>
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