Marsal,
Your aperture size in the stencil should be slightly smaller than the
pad size (perhaps a 10% reduction), especially when using a 7 mil
stencil. The additional amount of solder caused by a solder mask
thickness 1 mil higher than the pad surface does not help.
Also look at your print registration. No solder paste should be printed
onto the pwb (off the pad).
This may help reduce the number of solder balls trapped under the 1206
parts. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Marsal Tampubolon
Sent: Tuesday, February 27, 2007 3:59 AM
To: [log in to unmask]
Subject: [TN] Solder Ball Stick beneath of the chip resistor/ capacitor.

Dear   Tech  Netter..
Any one   in  forum  ever  facing  solder    ball   beneath   of  the
chip 
 cap  and  chip  resistor  ?  FYI  our  stencil  thickness  is  7  Mils 
and  majority  happen  on  1206  part   size.  Also   the   raw  PCB
it 
self  have  mask  with  thickness   around  1  Mils  which   defenetely 
increase  the   solder   paste  thickness  after  printing.   Any  thing

we  can  do  with  decrease  stencil   thickness  or   stencil  opening
to 
 resolve  this   issue  ?
Highly  appreciate   your   advice .

****************************************************
Regards... 
Marsal GM Tampubolon.
Senior   Quality   Engineer
CEI  Contract  Manufacturing, Singapore.
Batam  Plant,  Indonesia.

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