The reliability issues come into play when the misregistration results in
decreased
width of conductors where they come in contact with the barrel of the hole.
The
current carrrying capability is no longer what was designed, but that of much
thinner copper.  The trick is, when you have misregistration, to determine in
what
direction this occurs and are any conductor to hole runs affected.

There are some pretty good diagrams in 600 that show the various ways of
measuring the effects of breakout when conductor width is decreased.

Unfortunately with inner layers you must do horizontal microsections to
determine the values.  However, sacrificing one board to save a lot may be
worth it.

Susan Mansilla
Robisan Lab

##############################################################
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
##############################################################