Published in Proceedings of the 41st International Symposium on Microelectronics: Providence, RI, November 2, 2008.
Mobile and handheld electronic devices are prone to being dropped. This drop event may result in failure of solder joints inside these devices. The need for RoHS compliant boards coupled with the demand for reliable electronics has resulted in the development of the JEDEC Standard JESD22-B111 to standardize the method of drop testing surface mount electronic components. However, there has been little study on the effects of additional mass on the board and rigidity of the board on drop test reliability. This paper examines the drop impact dynamic responses of the JEDEC JESD22-B111 board. Of interest are the effects of an attached cable and rigidity of the board on the peak acceleration at different locations of the board. Fifteen 0.5 mm pitch CSPs were assembled on the board using SnAg3.0Cu0.5 lead free solder. The drop test was conducted using a Lansmont M23 TTSII Shock Test system. A half-sine shock impact pulse of 1500 G with 0.5 ms duration was applied to the drop table where the test vehicle was mounted. Two accelerometers were used to monitor the peak acceleration with one placed on the drop table and the other on the board at the component location. Statistical analysis showed that both the rigidity of the board and a cable attachment have an effect on the peak acceleration at individual component locations. Results show that the peak acceleration differs significantly at different component locations and the peak acceleration at some component locations are much higher than on the drop table. A cable attached to the board is shown to influence both peak acceleration and symmetry. A correlation between the peak acceleration and the number of drops until component failure was assessed.
Industrial Engineering | Manufacturing