Some do, some don't.
It depends on many factors, as ball size, pad design, aso.
Not printing the paste will have sometimes an undesired result of loss of
height, (thermal mismatch!), opens due to warping aso., but less solder
spheres between joints.
Noneutectic balls need solder paste.
Profiles might differe with or without.
Gaby
> ----------
> From:         Trevor Goddard[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Trevor Goddard
> Sent:         ?יום שני 05 פברואר 2001? 16:43
> To:   [log in to unmask]
> Subject:      [TN] BGA REWORK
> 
> Hi all.
> I have a question about reworing BGAs. Do you have to reprint the solder
> paste before placing the component or can you lay down some flux and rely
> on
> the solder balls of the BGA?
> Thanks in advance
> 
> Trevor Goddard,
> SMT Supervisor
> XLTEK
> (905) 829-5300 x 348
> [log in to unmask] <mailto:[log in to unmask]>
> 
> --------------------------------------------------------------------------
> -------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send the following message: SET
> Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
> E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
> ext.5315
> --------------------------------------------------------------------------
> -------
>