Carl, All Concerned:
- No conflict exists within IPC-A-610C regarding vertical fill of PTH's.  For
Class 3 products: Table 6-2 requires the vertical fill to be a minimum of
75%; Figure 6-5 on page 6-6 restates that if the vertical fill of hole is
less than 75% it is a defect for both Class 2 and 3.  Figure 6-7 on page 6-7
lists an exception that applies only to a Class 2 product.  That exception is
that it is Acceptable for a Class 2 product if the vertical fill of the hole
is only 50% as long as the limited vertical fill is due to a PWB design that
results in thermal swamping of that particular PTH (note that adjacent PTH's
are required to meet the requirements of Table 6-2).  The indication that the
50% vertical fill applies only to a Class 2 is found adjacent to Figure 6-7
where it says that: 1) no vertical fill requirement is specified for Class 1
(consistent with the requirement of Table 6-2),  2) 50% vertical fill is
acceptable for Class 2 ONLY when it is known to be caused by heat sinking of
that specific PTH, and 3) less than 50% vertical fill of the PTH is a Defect
for Class 3 (consistent with Table 6-2 and the Defect listed adjacent to
Figure 6-5.
Hope the above clarifies the intent of the requirements.  By the way, the IPC
is preparing to publish a document called IPC-HDBK-610 (or something like
that).  It is, as the name implies, a handbook that explains the rationale
behind, and reasons for, some of the requirements in IPC-A-610.
Regards, Jim Moffitt, Moffitt Consulting Services, Noblesville IN

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------