Clinton Windsor,

   My process engineer has reported seeing solder balls around the
   components after solder reflow.
   He is running this particular board in a no-clean process using
   Alphametal LR-725 solderpaste, HASL PWB and without N2 at reflow.

   Experiments show that turning the N2 on reduces the solder balls
   dramatically.
   However, due to cost constraints, it is necessary to run without
   N2.

   Is this the " squeeze balls " that you mentioned ?

   Matthew,

   Can you fax me the aperture shape definition ?
   My fax number is 011-604-5064447

   Thanks.

   Jerome Yeo

   [log in to unmask]


> -----Original Message-----
> From: Jay DeKing (EMA) [SMTP:[log in to unmask]]
> Sent: Tuesday, January 20, 1998 12:50 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Stencil Aperture Shapes -Reply
>
> Matthew,
>
> Please fax me the paste aperture shape definition. My fax number is
> (716)334-3481.
>
> Thanks,
>
> Jay DeKing
> EMA Mid-Atlantic, Inc.
> (716)334-2970 voice
> (716)334-3481 fax
> [log in to unmask]
>
> -----Original Message-----
> From:   Matthew Park [SMTP:[log in to unmask]]
> Sent:   Wednesday, January 07, 1998 11:37 AM
> To:     [log in to unmask]
> Subject:        [TN] Stencil Aperture Shapes -Reply
>
> Mr. Windsor:
> Post your fax number, so I may fax you a solderpaste
> aperture shape that I use for the complete elimination of
> solderballs for chip components.  It was proven it works
> better than home plate shape.
>
> regards
> Matthew Park
>
> >>> Clinton Windsor
> <[log in to unmask]> January
> 7, 1998  1:27 am >>>
> 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
> ##############################################################
>
> ##############################################################
> 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
##############################################################