首页> 外文会议>International Conference on Soldering and Reliability >BOARD LEVEL RELIABILITY EVALUATION OF LOW SILVER (AG) CONTENT LEAD-FREE SOLDER JOINTS AT LOW STRAIN RATES
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BOARD LEVEL RELIABILITY EVALUATION OF LOW SILVER (AG) CONTENT LEAD-FREE SOLDER JOINTS AT LOW STRAIN RATES

机译:低银(Ag)含量低应变率的低银(Ag)含量无铅焊点的棋盘级可靠性评估

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To improve the durability of lead free solder joints under high strain rates, such as drop and shock loading, some area array manufacturers have converted to low silver (Ag) content tin silver copper (SAC) solder spheres instead of the commonly accepted SAC305 solder. While the lower silver content SAC solder joints may address high strain rate shock loads, the durability of these joints under low strain rates has to be taken into consideration. The objective of this study is to assess the reliability under loading conditions with strain rates several orders of magnitude below that observed in drop testing. To this end, thermo-mechanical loading induced by temperature cycling (-55°C to 125°C) and mechanical loading induced by cyclic board level mechanical torsion were considered. Test vehicles were assembled using SAC305 solder paste with eight peripheral ball grid array packages (BGA) per printed wiring board with SAC105, SAC125Ni and SAC305 solder spheres. Four test specimens per type were assembled. Two of test specimens of each solder combination were then subjected to temperature cycling, while the remaining two were subjected to mechanical torsion. In-situ electrical resistance monitoring was performed on the low electrical resistance paths formed by the individual packages and the printed wiring board. Statistical analysis was conducted on cycles to failure data collected from the defined tests. A drop in fatigue durability with decrease in silver content in the solder spheres was observed for both thermo-mechanical and mechanical loading.
机译:为了提高高应变率下铅免焊缝的耐久性,如下降和冲击载荷,一些区域阵列制造商已经转化为低银(AG)含量锡银铜(SAC)焊球代替常用的SAC305焊料。虽然下银含量囊焊接接头可以解决高应变速率冲击载荷,但必须考虑在低应变率下这些关节的耐久性。本研究的目的是评估在负载条件下的可靠性,其中应变率在下降测试中观察到的几个数量级。为此,考虑了温度循环(-55℃至125°C)诱导的热机械载荷和通过循环板级机械扭转诱导的机械载荷。使用SAC305焊膏组装试验车辆,每个印刷线路板,SAC105,SAC125NI和SAC305焊球。组装了每种类型的四种试样。然后对每个焊料组合的两种测试标本进行温度循环,而剩余的两种待进行机械扭转。对由各个包装和印刷线路板形成的低电阻路径进行原位电阻监测。在从定义的测试中收集的故障数据进行统计分析。对于热机械和机械负载,观察到焊球中银含量降低的疲劳耐久性降低。

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