Justin,

As far as I know, the number 3 that came up in other replies is based on the
fact that all moisture sensitive components, including PBGAs, are
pre-conditioned with 3 reflow cycles prior to package qualification (ref.
J-STD-020 and J-STD-033). This is done right after soaking the parts to
their specified moisture content. This means that you can rely on the fact
that the parts will survive at least 3 reflow cycles at their maximum floor
life which is defined by their MS level. Beyond that, there is no data to
guarantee the reliability of the component. Of course if you bake the parts
prior to reflow you will reduce the concern relative to moisture/reflow
damage. On the other hand, there is also a limit specified for the maximum
number of bake cycles at 125C (currently only one bake cycle allowed),
because of solderability issues.

As someone already pointed out, boards with BGAs on both sides imply at
least two reflow cycles to begin with. Removal, re-attachment and reballing
should also be considered if the package body exceeds 200C. This is the
critical limit set by the IPC/JEDEC standard to define a reflow cycle which
can cause potential internal damage to the parts.

I hope this is helpful.

Francois Monette
Cogiscan Inc.
Tel : 450-534-2644
Fax : 450-534-0092
E-mail : [log in to unmask]
www.cogiscan.com



Date:    Thu, 21 Mar 2002 14:27:48 -0000
From:    "Braime, Justin" <[log in to unmask]>
Subject: BGA reballing

Hi guys,
I am looking at using the SolderQuik preforms for reballing some BGAs, but I
am concerned about the reliability of this process in terms of the number of
thermal cycles being sustained by the BGA component. Does anybody know of
any studies done on this?

Thanks

Justin Braime
Senior Production Engineer

Racal Instruments Ltd
480 Bath Rd, Slough
Berkshire, SL1 6BE
England

Tel: +44 (0)1628 604455
Fax: +44 (0)1628 662017
E-mail: [log in to unmask]

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