Hi ya'll!

I got called back to incoming this morning to look at a PTH board that shows
exposed copper, but it's only at the side edges around the periphery of the
anular pads...it's like this over the whole board. The top surfaces have
tin/lead plating, but not the side edges.

                            Top surface of pad is plated
                                               |
                                ________V_________
__________________|__________________|__<-----Exposed copper on sides

                                            PCB

Is this a defect? Looked in the IPC-A-600F on page 85, (3.3.10 Solder coating
thickness) and there's a conflicting statement I think. It says; Acceptable -
Class 1,2,3, "Solder coating thickness is uniform. Vertical (conductor and
land) areas may not be covered. No exposed copper is evident."

On one hand it says that the vertical surface may not be covered, but on the
other hand it says you can't have exposed copper. If the vertical surface
doesn't have to be covered, then you're gonna have exposed copper. So which
is it?

Also there's a statement at the bottom of the page that visual observations
are made on cross sections only. I can see this with my own two
eyeballs...don't need a cross section to see it.

This board is for a hi-rel product by the way....

Thanks!

-Steve Gregory-

##############################################################
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 Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################