基于故障物理的集成控制器电路板可靠性预计

目的实现商用电动汽车集成控制器的可靠性预计与提升,采用应力仿真与故障物理相结合的方法对其关键电路板进行可靠性预计。方法针对集成控制器的数字样机,开展热、振动仿真应力分析,采用故障模式机理及影响分析(FMMEA)方法,分析电路板可能存在的故障模式和故障机理,确定潜在故障模式的故障物理模型。将应力分析结果作为故障物理模型的输入,进行基于故障物理的可靠性预计,寻找设计薄弱环节,并提出改进措施。结果找到了电路板的8个高温器件和热集中区域,振动仿真分析表明,电路板顶端与中心振动强度较大,可能引起疲劳失效,需要给予关注。通过FMMEA分析,得到电路板的主要故障模式为焊点开裂,主要受温度循环影响,造成热疲劳失效。最后采用Coffin-Mason模型,计算得到电路板的平均故障间隔时间为15869 h,找出了电路板的可靠性设计的薄弱环节。结论该方法基于故障物理,相对传统基于手册的可靠性预计方法精度更高,同时能够在产品研制阶段与性能设计并行,通过分析和改进产品设计,达到正向可靠性设计的目的,为新能源汽车领域电子产品的可靠性预计提供新的思路。

Reliability Prediction for Integrated Controller Circuit Board Based on Physics of Failure

In order to achieve the reliability prediction and improvement of the integrated controller of commercial electric vehicles, the method of combining stress simulation and physics of failure is used to predict the reliability of its key circuit boards. The thermal and vibration simulation stress analysis was carried out for the digital prototype of the integrated controller. The failure mode mechanism and effect analysis (FMMEA) method is used to analyze the possible failure modes and failure mechanisms of the printed circuit board, and the failure physical model of the potential failure mode is determined. The results of the stress analysis are used as the input of the failure physical model, the reliability prediction based on the physics of failure is performed, the weak points of the design are found, and the improvement measures are proposed. Through the thermal simulation and vibration simulation analysis of the key circuit board of the integrated controller, eight high-temperature devices and thermal concentration areas of the circuit board are found. The vibration simulation analysis shows that the top and center vibration strength of the circuit board is large, which may cause fatigue failure, so attention should be paid to it. FMMEA analysis shows that the main failure mode of the circuit board is solder joint cracking, which is mainly affected by temperature cycling and caused thermal fatigue failure. Finally, the Coffin-Mason model was used to calculate the average failure interval of the circuit board is 15869 h, and the weak links of the circuit board reliability design can be found out. This method is based on physics of failure, which is more accurate than the traditional manual-based reliability prediction method. At the same time, it can be parallel with performance design during the product development stage. It can achieve the purpose of forward reliability design by analyzing and improving the product design, for the new energy automotive electronic product reliability prediction is expected to provide new ideas.