单板计算机的故障模式与机理及影响分析

Failure Modes, Mechanisms and Effects Analysis of Single Board Computers

故障模式、机理及影响分析((FMMEA)是研究产品的每个组成部分可能存在的故障模式、故障机理并确定各个故障模式对产品组成部分和功能的影响的一种可靠性分析方法。详细介绍了对单板计算机进行FMMEA的实施过程,包括系统定义,确定潜在的故障模式,分析故障原因、故障机理、故障影响等一系列的过程。对单板计算机进行了有限元建模,并通过热应力分析和振动应力分析,得到了其在不同环境下的温度分布、振动模态等信息,为故障物理模型提供输入。利用各种故障物理模型对单板计算机各单点的故障进行了定量的计算。分析结果表明:由温度循环引起的小外形封装(SOP)的随机存储器芯片的焊点疲劳故障的故障前时间最短,是整个电路板的薄弱环节;焊点热疲劳故障为单板计算机主故障机理,在实施PHM过程中要重点监测该部位的故障状况。

Failure Modes, Mechanisms and Effects Analysis （ FMMEA） is a kind of reliability analysis method to study the possible failure modes and failure mechanisms of each component of products, and to identify the effects of various failure modes on the components and functions of productes. The way to implement FMMEA for the Single Board Computer, including defining the system, identifying the potential failure modes, and analyzing the causes, mechanisms and effects of the failure, are introduced in detail. And the finite element analysis has been adopted to carry out the process of FMMEA for the Single Board Computer.Besides, through thermal stress analysis and vibration stress analysis, temperature distribution and vibration modes under different environment are obtained, which are the inputs of physics model of failure. And then the quantitative calculation of single point failure of the Single Board Computer is carried out by using a variety of physics of failure models. Results show that the time to failure （ TTF） of random access memory chip with SOP （ small outline package） is the shortest and the failure is due to solder joint fatigue failure caused by the temperature cycle.It is the weak point of the entire circuit board. Thus solder joint thermal fatigue failure is the main failure mechanism of the Single Board Computer. Therefore, in the implementation process of PHM for the Single Board Computer, the failure condition of this position should be monitored intensively.