We do not use paste for reworking PBGA's. A good no clean paste
     flux, proper pad preparation and appropriate "no clean" profile will
     provide you excellent results. We have the capability to also use the
     paste printing method, but our investigations have shown that the
     paste flux method yield more consistent results than the solder paste
     method.  Specifically, the BGA joint size is more uniform and there
     are fewer and smaller voids introduced into the joints with paste
     flux.  We have never experienced opens with either process.

        Our have been confirmed with HP (Laminography), Fein Focus (Oblique
     Transmission) and functional testing. We have been using this process
     for 2 years with 100% yield.

     Thanks,
     Mark McAuley
     Process Engineer
     Hitachi





______________________________ Reply Separator _________________________________
Subject: [TN] BGA Rework
Author:  Stephane Richard <[log in to unmask]> at Internet-HICAM-OK
Date:    2/11/98 9:29 AM


We currently use solder paste when we do rework on PBGA's.

I m interested in knowing if it is required.  I heard that the paste was
not required for PBGA's, only for CBGA's.  Is that true ?  If so, do we
only have to put flux on the board to be rework before putting the new PBGA ?

Thank in advance.


------------------------------------------------
Stephane Richard
Ingenieur de procedes
Process Engineer
Matrox Electronic Systems Ltd
E-mail: [log in to unmask]
Telephone:(514)969-6000 ext.7585
Pagette : (514)201-0044
Fax:      (514)685-3415
-------------------------------------------------


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