Technetters,

        We're having a voiding problem on a 0.75 mm micro-BGA, the voids
size fluctuate from 15-40% of the pad area, we only have a 2D X-ray so there
is no way of determining the void size or the void location. IPC states that
is a process indicator if the voids stays within the 10-25% limit of the
solder ball to board interconnection. We're using a soak profile with a peak
temperature of 215-220 degrees, the soak extends for 110 seconds from
140-170, time above 183 is 60 secs and ramp rate stays below 1.5 C/sec. Is
there something we can do to eliminate or reduce the problem?, are voids a
real issue?

Any comments would greatly appreciated

Jorge Rodriguez
Process Engineer
Varian Electronics Manufacturing
615 South River Drive
Tempe, AZ 85281
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