Qualification of the Assembly Process of Flip-Chip BGA Packages ...

Cleaning
Texas Tech University, Nivetha Shivan, May 2012
De-ionized water ultrasonic cleaner is used for ultrasonic (38 kHz) cleaning for minimum
15 minutes. This ensures devices are cleaned and are free of flux residues.
Drying
The units are subjected to drying for 5 minutes at 125 deg C or at room temperature until
dry. This ensures devices are dry prior to electrical tests.
Visual inspection: The units are visually inspected which helps check for damage during
reflow process.
5.1.1.3 CSAM after MSL pre-conditioning
CSAM analysis is performed on the devices to check for any delaminations/voids in the
package.
5.1.1.4 Temperature Cycling and Pressure Cooker Test
Following MSL, the units are subjected to stress tests like temperature cycling and
pressure cooker test. The read points for temperature cycling were after 500 cycles and
1000 cycles. Similarly, the read points for pressure cooker tests were after 168 hours and
288 hours.
5.1.1.5 Final Measurements
Visual examination and CSAM analysis are performed on the devices.
5.1.1.6 Shadow Moiré Test
The warpage of the package was measured on the substrate surface. These measurements
are conducted at following temperatures: 25°C, 100°C, 150°C, 183°C, 200°C, 220°C,
240°C, 260°C, 240°C, 220°C, 200°C, 183°C, 150°C, 100°C, and 25°C.
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