Having never done this myself, may I offer an idea for the next time. If you
have the room, (and with a BGA who does) screen print or in etch, some marks
to line up the device from either a top view, (watch the parallax) or row /
column aligned with the pins. Just my $.02 worth on the subject.

Regards,
Scott Decker

                     AKA: PadMasterson
   /\     Sr. PCB Designer, Portland
  /\/\    7245 NW Evergreen Pkwy., Suite 100, Hillsboro OR 97124
 /\/\/\   (503)531-2050 ext. 1820 FAX: (503)531-2051
/\/\/\/\ [log in to unmask] <mailto:[log in to unmask]>
 Praegitzer Industries, Inc.
The Fine Line in Printed Circuits




        -----Original Message-----
        From:   [log in to unmask] [SMTP:[log in to unmask]]
        Sent:   Thursday, July 22, 1999 10:47 AM
        To:     [log in to unmask]
        Subject:        Re: [DC] BGA Assembly by hand

        we place many BGA's by hand, in fact it can be fairly easy.  The
        screenprinting is critical and the placement very important.  We
build many
        prototype assemblies that are not worth setting up on the placement
machines,
        the bga's are placed by hand.  in general we focus on the following:
        - very fresh paste,
        - place the part in a very well lit area
        - use a very very low vision angle (almost lay your head on the
table) and
        using a vaccum pen to hold the part place it on while lineing up the
rows of
        balls with the rows of solder bumps.  this does take some practice.
        - do not ever push down on the part
        - look at the part from all four sides until all the balls line up
with the
        solder pads.
        - try taking the part off  before reflow you will see that the
solder will
        generally hold
         up even after pushing the part around a bit (not too much though)
        -take your time, some parts are trickier than others but we have put
down
        just about anything..

        any questions send me a line
        [log in to unmask]