Interface Fracture Mechanics of Laminates and Its Application to Design of LSI Packages

1.研究了由两个不同弹性和热性能梁组成的层合板在机械载荷和热载荷作用下的分层扩展问题，分析了层合板界面断裂力学中的两个基本模型。（一）本文考虑了垂直于含脱层边缘层合梁表面的低速冲击。根据时变外力作用下的瞬态振动理论，分析了梁的动力响应。假定冲击杆的速度条件为经过一段短暂的瞬态时间后速度变为常数。然后，由下式确定冲击力的大小：利用拉普拉斯变换法，得到了脱层边缘附近弯矩的闭合形式，并由此计算了脱层梁的能量释放率，同时进行了实验研究，实验结果表明，理论预测的脱层梁的响应与理论结果吻合较好。（2）分析了含脱层梁在温度梯度作用下的脱层扩展问题，结果表明，当温度梯度小于某一临界值时，假定脱层表面接触的模型是有效的，此时能量释放率恒为零，而当温度梯度达到某一临界值时，脱层扩展问题的能量释放率为零，当温度梯度大于某一临界值时，脱层扩展问题的能量释放率为零，当温度梯度大于某一临界值时，脱层扩展问题的能量释放率为零。发生局部脱层屈曲，能量释放率不再为零;这表明脱层扩展只能通过局部脱层屈曲来实现。本文用Kr 85放射性示踪技术，对大规模集成电路（LSI）塑料封装在温度循环试验中出现的边缘分层的初始位置进行了识别，并与分析结果进行了比较。

1.Delamination growth due to mechanical and thermal loadings is investigated for laminates consisting of two beams with different elastic and thermal properties.Two basic models, which are important for the fracture mechanics of interface of laminates, are analyzed.(1)The low velocity impact applied normal to the surface of laminated beam with an edge delamination is considered.The dynamical response of the beam is analyzed on the basis of the theory of transient vibration due to time varying externally applied force.The condition of the velocity of impacting bar is assumed as such that the velocity becomes constant after some short transient time.The magnitude of impacting force is then determined by making use of Laplace transform method.The bending moments near the edge of delamination are obtained in closed form, from which the energy release rate is calculated.Experiments are also conducted, which show that the predicted response of the beam agree well with the theory.(2)Delamination growth due to temperature gradient is analyzed for the beam with an internal delamination.It is shown that when the temperature gradient is below some critical value the model assuming the contact of the delaminated surfaces is effective and in this case energy release rate is identically zero.However, when the temperature gradient reaches some critical value, local delamination buckling occurs and energy release rate becomes no longer zero ; This implies that the delamination growth would occur only through the local delamination buckling.2.Numerical analyses based on FEM and experiments are made for delamination growth in large-scale integrated circuits(LSI)plastic packages.Using Kr 85 radioactive tracer techniques, initial sites of edge delaminations occurring during temperature cyclic tests in LSI plastic packages areidentified and the results are compared with analyses.