Dear SVA patro

Regarding your queswtions about rework of BGA

1. if you heat up more than 185°C the shape of the Ball will be somewhat
spherical ( tear drop ) depenting on the cooling time ( whether you leave
enough time to to the liquid solder to form a sphere). The size of the ball
is completely undetermined.
2. I wouldn't.
3. --
4. X-ray
5. Transmission X-ray: yes in skilled personel is on work
Voltage: depending on the board ( thickness of copper where the x-rays have
to go through). 60-80 kV are usually more than sufficient. If you have too
much noise use a higher filament current ( 0.05-0.075mA )

Best regards
Guenter Grossmann
Federal Institute of Technology Zuerich
Switzerland


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