An electronic device consists of electronic components attached on a circuit board. Reliability of such a device is limited to fatigue properties of the components as well as of the board. Printed circuit board (PCB) consists of conducting traces and vertical interconnect access (via) out of copper embedded in a composite material. Usually the composite material is fiber reinforced laminate out of glass fibers and polyimid matrix. Different reasons play a role by choosing the components of the laminate for the board, one of them is its structural strength and fatigue properties. An improvement of board’s lifetime can be proposed by using computational mechanics. In this work we present the theory and computation of a simplified one layer circuit board conducting electrical signals along its copper via, producing heat that leads to thermal stresses. Such stresses are high enough to perform a plastic deformation. Although the plastic deformation is small, subsequent use of the electronic device causes accumulating plastic deformation, which ends the lifetime effected by a fatigue failure in the copper via. Computer simulations provide a convenient method for understanding the nature of this phenomenon as well as predicting the lifetime. We present a coupled and monolithic way for solving the multiphysics problem of this electro-thermo-mechanical system, numerically, by using finite element method in space and finite difference method in time.

中文翻译：

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改善电路板可靠性的计算研究

电子设备由附在电路板上的电子组件组成。这种设备的可靠性限于部件以及板的疲劳特性。印刷电路板（PCB）由嵌入复合材料中的铜制成的走线和垂直互连通道（通过）组成。通常，复合材料是由玻璃纤维和聚酰亚胺基体制成的纤维增强层压板。选择用于木板的层压板的组件有不同的原因，其中之一是其结构强度和疲劳性能。可以通过使用计算机制来提高电路板的使用寿命。在这项工作中，我们介绍了一种简化的单层电路板的理论和计算方法，该电路板沿其铜过孔传导电信号，并产生导致热应力的热量。这样的应力足够高以进行塑性变形。尽管塑性变形很小，但是电子设备的后续使用导致累积的塑性变形，这终止了由铜通孔中的疲劳故障影响的寿命。计算机仿真为了解这种现象的性质以及预测寿命提供了一种方便的方法。我们提出了一种通过空间有限元法和时间有限差分法数值求解该电热机械系统的多物理场问题的耦合整体方法。从而终止了因铜过孔疲劳故障而导致的使用寿命。计算机仿真为了解这种现象的性质以及预测寿命提供了一种方便的方法。我们提出了一种通过空间有限元法和时间有限差分法数值求解该电热机械系统的多物理场问题的耦合整体方法。从而终止了因铜过孔疲劳故障而导致的使用寿命。计算机仿真为了解这种现象的性质以及预测寿命提供了一种方便的方法。我们提出了一种通过空间有限元法和时间有限差分法数值求解该电热机械系统的多物理场问题的耦合整体方法。