Research On The Frequency Characteristic Of Lead-free Solder Joint Damage Under Stretch And Impact By Lab VIEW

Lead-free solder joint failure is the main cause of electronic devices failure, and the damage of lead-free solder joint under vibration impact are becoming increasingly serious. The frequency characteristic under stretch and impact is an important factor of solder joint. The researches of solder joint vibration failure both at home and abroad are reported to be mainly concentrated on the high-frequency conditions that the frequency is higher than50Hz. The paper made a research on the low-frequency characteristic of single Sn-3.5Ag solder joint damage under stretch and impact by the way of theoretical simulation> experimental measurement and so on.The theoretical relationship between lead-free solder joint damage rate and stretch impact frequency spectrum was established. And based on the high-order harmonic components of waveform, the frequency characteristics of solder joint damage under three different kinds of stretch impact waveform were simulated. The results showed that:(1) When the frequency of any waveform loads was the same as the inherent frequency of solder joint, the solder joint damage rate reached the maximum;(2) When the frequency was lower than inherent frequency, the solder joint rate decreased with the decrease of frequency, but there were several secondary peaks of solder joint damage rate under square wave loads and triangular wave loads;(3) When the frequency was higher than the inherent frequency, the solder joint damage rate decreased with the increase of frequency.Based on the theoretical relationship between solder joint’s mechanical damage and electrical characteristics, the testing system of solder joint damage under stretch and impact was designed and carried out by measuring resistance, and NI DAQ was used as hardware core of the testing system which was developed by Lab VIEW. Then the testing system was used to do research on solder joint, the results showed:In the low frequency range of4-16Hz, the secondary peaks of lead-free solder joint damage turned up at the frequency point of6Hz and MHz, and the damage rate at6Hz was greater.The solder joint damage rate reached secondary peaks at6Hz and14Hz both in experiment and emulation results by the method of comparative analysis. The secondary peaks of solder joint rate existence conditions was:harmonic component of square wave loads was equal to or close to the inherent frequency of solder joint, and the amplitude of that harmonic component was higher than9.1%amplitude of square wave loads.