May be you can keep the mask a comfortable distance away from the solder
joint.

        -----Original Message-----
        From:   Joy, Stephen C [SMTP:[log in to unmask]]
        Sent:   Tuesday, June 16, 1998 10:33 AM
        To:     [log in to unmask]
        Subject:        [TN] Solder mask profile information

             We have been having some problems with a BGA device where we
see
             ball fatigue (solder ball cracks) after temp cycling. We think
it
             may be related to severe undercut of the solder mask.

             Does anyone have information on different solder mask foot
             profiles? How difficult is it to get a straight sidewall on
             solder masks?

             Are there any that are much better than others for this
             attribute? What would be the trade offs?

             You can contact me off line if you prefer.

             Steve Joy
             503-696-2239
             [log in to unmask]

        ################################################################
        TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for
additional information.
        For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
        ################################################################

################################################################
TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################