Hi Stephane,

I'd say that it depends upon the PBGA.

We've found that most PBGAs do not require the addition of solder paste.
However, there is one that we use that is fairly large (35 mm) and which
has a tendency to curl up on the corners.  Without paste, the resulting
solder joints at these locations can be very thin or non-existent.
Microsections have documented this phenomenon well on this package.

Best regards,
Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
[log in to unmask]
----
Stephane Richard wrote:
>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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