People will claim many things... ask your PWB vendor if they plan to
screen soldermask from one side into the holes while pulling a
pseudo-vacuum on the whole board.... the only things that I have come
accross with filled vias is either a stand-off on the top side of the
via, or air entrapment on the bottom side where the via was not
completely filled and the bottom side LPI coat somehow trapped
air...this bubble may burst during assembly, thus exposing Cu and
serving as a site for contaminant accumulation, which may not be cleaned
properly...which then...which then....

Marcelo

> -----Original Message-----
> From: [log in to unmask] [SMTP:[log in to unmask]]
> Sent: Tuesday, November 11, 1997 5:41 PM
> To:   [log in to unmask]
> Subject:      [TN] Sealing Vias
>
> Among the ways of sealing vias on LPI solder masked boards are a)
> filling
> the vias with LPI, and b) tenting the vias with dry film solder mask.
>
> We are on the brink of converting from dry film to LPI on all our
> PCB's.  I
> would appreciate any comments on the relative merits/demerits of
> boards
> produced by these two processes.  Our supplier recommends the dry film
> option.
>
> Our boards are sometimes in relatively harsh environments and are
> designed
> to operate from -40 C to +70 C.
>
>
> Thanks to those of you who responded to my inquiry on how to repair
> urethane conformally coated boards which have been contaminated with
> silicone prior to conformal coating.
>
> ##############################################################
> 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.
> For the technical support contact Dmitriy Sklyar at [log in to unmask] or
> 847-509-9700 ext.311
> ##############################################################

##############################################################
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.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################