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0201 assembly plays a very important role in the continuing miniaturization of electronics products. After a systematic study using Sn‐Pb solder paste on pad design, machine evaluation, component qualification, and process optimisation, this study focused on the PCB assembly process for 0201 packages using Sn‐Ag‐Cu solder paste. The post‐reflow solder defects for a range of different spacings were examined for the different solder pastes.

Board level drop test is convenient to characterize the solder joint pcrfonnance, as it is mort controllable than s:-stein level drop. i.e. ccllular phone drop. A free fall board level drop tcsl was studied to compare the effectiveness with the cellular phone drop. Acceleration in both cases was measured to dcteniune the severity of tlie drop test. From this study, it can be concluded that the acceleration of PCB board cllangcs from 2700 to 6000G,'wluch is much largcr than that in system lcvcl drop. A large displacement of PCB board for board lewl drop was also rccorded but the warpage ai the locations of area array package and plastic strain of solder joints could be rclatively small. n u s may explain why most solder joints in the area army packagcs can survive more than 100 times of drop at the board level drop without failure. The iiicchanism of the board dcflection was studied and it is found that constraint on thc board edge played a kcy role. To get the same l c~c l of plastic strain in the solder joints as the system level drop. a simple fixture is suggested to constrain the boards. In this way. tlie board warpage and plastic strain of the soldcr joints in the board Icvel drop may bccoine closer to those in the syslcm level drop.