I agree with Werner. I spoke with a gentleman a while back from Baker Inteq. He
was doing some experimentation involving vacuolar porosity in solder joints. His
whole theory was that for years, all the way back to introduction of SMT,
everyone has been creating voids in the solder joints due to flux "pockets" in
the paste having no effective direction to out-gas. Therefore, when viewed by
Xray, small voids can be seen right at the junction of pad/lead. His intent was,
I believe, to open our eyes to something that has occuring all along. His
findings, at the point that we spoke, was that there was no reason to believe
this could be detrimental to the life of the joint. I used our Agilent 5DX to
look at some in-house boards since I could slice down to the micro level at
pad/lead junction. I too saw small voids where paste once was pre reflow. I had
no reason to believe this could decreas solder joint life. However, this was
performed only on leaded components, not BGA's. I would have no reason to
believe this to be any different with BGA's. Even though the lead and joint
between leaded and BGA are different, the mechanical alloy/intermetallic
structure are similar.
Jason Gregory
Production Supervisor
LaBarge Inc.
(918)459-2367
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Werner Engelmaier <[log in to unmask]> on 11/11/2002 06:10:45 PM
Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to
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To: [log in to unmask]
cc: (bcc: Jason Gregory/LABARGE)
Subject: Re: [TN] Void in BGA
Hi Yannick,
I would not spend much time on BGA SJ voids, since there is no real evidence
that they are in fact detrimental in normal produuct.
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com
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