OK, but I disagree!
        We at Sequent use rectangular pads and do not see a problem with
concentrating the solder at the joint.
        We do not require that the entire pad be covered with solder on the
final product.  This allows the assembly supplier
        to modify his solder stencil and make it oblong for better release of
the paste.

        The solder deposit shape does the concentration of solder fillet
along with the wettibility of the lead.  What we see is that
        all of the solder flows to the solder joint and leaves very little on
the unused portions of the pad.

        The advantage of routability with the oblong pad is not something
that adds much to the design as routing on a grid and
        using 45 DEG. corners is not compatable with a round feature.... not
a significant gain in my view.

        The biggest problem with a oblong pad is that it either has to be
drawn with the CAD system (creates a large Gerber file)
        or has to be constructed as a complex flash by the photoplotting
vendor.  All of this for no gain in my view!

        We did a test of oblong pads with rectangular pads on the same
design.  When we received the board, we could almost
        not identify the two designs, as the square corner is rounded in the
PCB etching process to a extent that it approaches
        the oblong.

        The question of pad shape vs stencil opening shape should be
separated, and are different with most assembly houses.
        Many articles have been published about different opening shapes in
stencils.  All are a advantage in each assembly house
        under their processes.  To think that the pad shape dictates the
stencil opening is a bad basic assumption!

        Please give me some feedback on the above.  I would like to hear your
reasoning for your position..

        [log in to unmask]


        -----Original Message-----
        From:   Gary Ferrari [SMTP:[log in to unmask]]
        Sent:   Tuesday, March 31, 1998 8:27 PM
        To:     [log in to unmask]
        Subject:        Re: [TN] oblong lands

        Marletta,

        It is preferred to have oblong lands to assist in concentrating the
solder fillet
        around the component lead. The IPC-SM-782 indicates oblong as
optional but should
        read preferred.

        Regards,


        Gary Ferrari
        Executive Director
        IPC Designers Council
        (860) 350-9300 Fax (860) 350-9309
        [log in to unmask]

        >>> Marletta Tucker <[log in to unmask]> 03/31/98 03:13PM >>>
        What is the deciding factor on whether or not an SMD parts land is
squared off
        or oblong?  Could/should all SMD parts have oblong lands?


          @ @ @                 Thanks,
        @ @ @ ///
         @    *                 Marletta Tucker
        @ @    >                1921 Hurd Dr. M/S 2-21
        @@|\ _                  Irving, Tx. 75038
        @ |                     972-518-7619
          #                     [log in to unmask]

        We have enough youth, how about a fountain of SMART?

        The above views are my own, and do not represent those
        of Abbott Laboratories.

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

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

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