Not silly. I am not an expert on paste but suggest you look at the soak before reflow. We had some voiding while qualifying a paste for a customer. We were using their recomended paste and profile. We had to increase the soak slightly because of the mass of the BGA.
Charle Caswell

-----Original Message-----
From: Yannick Brisson [mailto:[log in to unmask]]
Sent: Tuesday, January 28, 2003 8:29 AM
To: [log in to unmask]
Subject: [TN] Silly Question


Hi,

   I'm just wondering if someone could answer this silly question...we have
on a board some BGA and other discretes components, when we look at the
X-Ray picture we see that we have void (flux entrapment),  We look at our
BGAs and there are no trace of void before we pass it to the oven.  Our
finnish is a Tin Lead the surface is not flat( HASL), we check our profile
and everything is perfect.  Could our void could came from the finnish? like
this is not a flat surface could we find a void in the pad?? I know this
sound silly but I really don't see where those voids could came of.

  We didn't pass a empty board on the X-ray.


Thanks You

Yannick Brisson
============================
Technicien SMT
Technician SMT
M2S Électronique
2855, Rue de Celles 
Québec, Québec
G2C 1K7
Téléphone: (418) 842-1312 Ext: 264
Télécopie: (418) 842-0123
[log in to unmask]
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