We have had success with "home plate" at 80%.  You could also look at
the pad gap "A" and the distance between the component terminations.
If you move the pads apart on the caps it will reduce the "solder beads"
but, if you move the pads to far apart you will reduce the heel fillet.


>>> Clinton Windsor <[log in to unmask]>
01/07/98 03:27am >>>
Dear Technetters,

We are trying to eliminate the occurence of solder balls in our
production line by trialling various aperture shapes and reductions on
the screen printer stencil.  The nature of the solder balls suggests
that paste is being trapped under the component and then forms a solder
ball which adheres to the side of the component.  I have seen this type
of solder ball referred to as a "squeeze ball".  We have tried the so
called "home plate" (trapezoidal) shaped apertures with considerable
success on nearly all the components except for the 0603 capacitors.

I would be interested to hear any ideas or suggestions of other aperture
shapes or designs which could help solve this problem.

Thanks in advance,
Clinton Windsor

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