Carl,

Blind vias in the pads would contribute to any voiding.

joe

-----Original Message-----
From: Carlr Ray [mailto:[log in to unmask]]
Sent: Wednesday, July 02, 2003 8:19 AM
To: [log in to unmask]
Subject: [TN] BGA Viods


Hello All,
  I have a question (more like a poll I guess), concerning voiding of
BGA devices.
  I have PBGA 480 IO paremeter grid device and I am seeing lots of
voiding. Per the x-ray I am well within the IPC spec of 35% but I am
still having failures at ICT (OPENS). Once I reviewed the profile I
noticed we were not hitting the dewell time for flux activiation
recommended by the solder paste vender (min 60 seconds) and we were
seeing an extended time above 183c. We have changed the profile but some
of my companions feel that the size of the pad and amount of solder
paste is effecting the voiding. I disagree with them and feel that not
activiating the fluxes and extended time above liquidous is a major
contibutor to the voids.
  So now my question, what impact does the pads have with the voiding
of the spheres on the BGA?

Carl Ray
Sr. Manufacturing Engineer
Huntsville, AL 35807
Phone: 256-882-4800 ext. 8845
Cell: 256-990-1990

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