Board level drop test is convenient to characterize. The solder joint performance, as it is more controllable than system level drop, i.e. cellular phone drop. A free fall board level drop test was studied to compare the effectiveness with the cellular phone drop. Acceleration in both cases was measured to determine the severity of the drop test. From this study, it can be concluded that the acceleration of PCB board changes from 2700 to 6000G, which is much larger than that in system level drop. A large displacement of PCB board for board level drop was also recorded but the warpage at the locations of area array package and plastic strain of solder joints could be relatively small. This may explain why most solder joints in the area array packages can survive more than 100 tunes of drop at the board level drop without failure. The mechanism of the board deflection was studied and it is found that constraint on the board edge played a key role. To get the same level of plastic strain in the solder joints as the system level drop, a simple fixture is suggested to constrain the boards. In this way, the board warpage and plastic strain of the solder joints in the board level drop may become closer to those in the system level drop.
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