A high-speed test board design for 40GHz Bandwidth die

It causes great challenge to the ordinary method to test the performance of the die when it comes to high frequency like 40GHz, especially for the optical die with some peripheral units, which causes extra difficulties with probes on the test bench. For the discontinuity of the impendence causes great loss for high-frequency signal, and it is difficult to place the die and the optical peripheral units on the test bench and to find a proper posture to conduct a precise experiment. A test board with a 3.5mm cable connector was designed to overcome these difficulties and to reduce the unnecessary loss caused in the test procedure. Dies connects to the test board via wire-bonding or flip chip. The trace/spacing changes from 70/30um to 880/560um. Considerable simulations were performed mainly for two purposes. Firstly, the model of 3.5mm connector and the connection with board was established in HFSS to search for the less discontinuities of the connector connecting to the board to reduce the loss in the process of the signal transmission. Secondly, the simulations of different trace design help to choose the route with less loss. Aside from the structure design, process and material and structure must be optimized to improve the performance of this package structure.