Siegmund / Werner,

The voiding is only present on a single product, an Altera uBGA 88pin
device.
The ball size is 0.45mm (Tolerance +/-0.05) of Tin-lead alloy (63/37).  We
are using a 5thou thick stencil with a round aperature of 0.4mm.  Solder
paste is AIM253.  I have Xrayed the device by itself and it has no voids
prior to assembly.

Simon.

-----Original Message-----
From: Zweigart, Siegmund [mailto:[log in to unmask]]
Sent: Monday, 22 July 2002 7:20 PM
To: 'Simon Howells'
Subject: RE: [TN] BGA Void Formation


Hello Simon
We got similar problems for a CSP.
Therefore my questions:
Is the voiding correlated with one BGA- manufacturer?
What is the ball size?
Which past do you use?

We think that the problems are mainly correlated to the combination of the
flux with residues left on the balls. In our case the problem is clearly
correlated with on CSP- Supplier not with the package Type.


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-
Kind regards / Mit freundlichen Grüßen

Dr. Siegmund Zweigart
New Technology Manager

Solectron GmbH
Solectronstrasse 2              Fon. ++49 7032 998 194
D - 71083 Herrenberg         Fax  ++49 7032 998 222

e-mail: [log in to unmask] <mailto:[log in to unmask]> 
internet: www.solectron.com <http://www.solectron.com> 
----------------------------------------------------------------------------
-

        ----------
        From:  Simon Howells [SMTP:[log in to unmask]]
        Sent:  Montag, 22. Juli 2002 07:58
        To:  [log in to unmask]
        Subject:  [TN] BGA Void Formation

        Hi all,

        For one of our new products we are seeing a very high percentage of
voids in
        some of the BGA solder joints (just under 25% very close to IPC's
maximum
        allowable limit).  I have searched the technet archives trying to
find
        information on the causes and remedies on void formation but there
is very
        little detailed information on this subject.

        Does anyone have or know of a document / web address were I could
find some
        detailed information on this subject.

        Thanks,



        Simon Howells
        SMT Process Engineer
        GPC Electronics Pty Ltd

        Email:     mailto:[log in to unmask]
        Web:  http://www.gpc.com.au

	
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