In a message dated 12/14/2006 5:32:18 P.M. Eastern Standard Time,
[log in to unmask] writes:

So that  I might learn something here as well, wouldn't poor drilling tend
to
cause more of a hole void instead of a ring  void?


To me, poor drilling does either of two things - it rips the glass and  makes
a very rough hole, or there is resin smear (melted epoxy) in the entire
barrel.

Rough holes are very easy to spot when cross-sectioned in the 45 degree  mode
(discussed on TechNet a couple weeks ago).  That is, section in the  1:30 to
7:30 and 4:30 to 10:30 directions, as if the hole were a clock  face.  Rough
drilling traps bubbles preventing electroless or direct plate  deposition.
That results in blow holes, but not really in circumferential  voids, as seen
here.

Entire drill smear on the hole wall may plate, but you get massive
hole-wall-pull-away when the board sees assembly heat.  Sometimes this is  so bad the
hole wall buckles and it looks like a "5 point star" from the top  down, not a
circle.

To me massive voids says the electroplate copper had nothing conductive to
carry current in the hole. Now, I am wondering why there is any copper in the
center of the hole.  A good cross section will let the fab shop know the
problem source.

Denny Fritz
MacDermid.

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------