Thanks for your quickly and helpful reply.

1. Given that we will make a new PCB model, my advisor told me that we will just make the IC chip rigidly glue together with the PCB, there is no special physical connection between them. I thought that we do not need to consider the problem of Dual In-Line or Ball Grid.

2. Since I found out a small issue that If the time span is not large enough for the whole simulation, the Jump-up or Jump-down phenomenon will not happen, but after I change the total time from 10s to 20s. there is a convergence issue happens which said that one of the element have excessive distortion. Could you give me some suggestion for that, I also attach it, besides sometimes if I increase the number of the elements, the problem will not be occurred, but sometimes it does not work. Do you know the reason why?

Best Regards

Xiaofu Li