1. The main reliability problems in Ball Grid Array (BGA) and Pin Grid Array (PGA) packages are caused by the following (choose all that apply):
1. The solder joints are not inspectable
2. Vibration
3. Absorbtion of moisture
4. Solder creep and thermal coefficient of expansion mismatch
2. What is the cause of the main reliability issue with plastic encapsulated integrated circuits?
1. Moisture absorbtion
2. Growth of tin whiskers
3. Mechanical stress on the chip from the encapsulation
4. Lack of heat transfer