Technetters:
What is your opinion on tenting of vias with LPI soldermask? If a design
gives leaves the mask film open over vias, the mask will be UV-exposed,
though not to the degree of the mask on the surface, resulting in some mask
coverage of copper inside the vias, but not as durable/thick as that on the
surface. Some of it will remain, some may end up HASL'ed. What is the
reliability of the "in-between" surfaces that don't coat with solder, but
also don't appear to be covered with mask? The "old specs" used to allow
some "haloing" around pads where thermal cured mask tapered off and left a
coppery ring around the solder-coated pad. Is this the same thing, and is it
a concern?
Designers/end users: If your design allows the vias to be covered with mask,
but the vias don't fill with mask, what problems do you foresee?
Thanks for any and all replies.
G'day
Timothy Reeves
ECD Circuit Board Division
13626 South Freeman Road
Mulino, OR 97042
[log in to unmask]
(503) 829-9108 (800) 228-8198  FAX (503) 829-5482

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