A study of a low-loss and ultra-wide band transmission structure through BGA based on HTCC technology

This paper presents a type of ultra-wide band transition connected by BGA. One part is a strip line interconnected to a vertical quasi-coaxial line, and the other part is a vertical quasi-coaxial line interconnected to a coplanar waveguide, the two parts are connected by BGA. This structure has the advantages of broadband, low loss and small size, and can be used for multilayer System-in-Package (SIP) and Multi-Chip-Module (MCM) applications. It can work in an ultra-wide band from DC to 35GHz, the return loss is better than -15dB, and the maximum insertion loss is only 0.4dB. In addition, the shape of the solder ball and the size of the pad were simulated and analyzed, which shows that the simulation results are not much different whether it is cylinder or a drum-shaped ball and could be ignored in the simulation. So take the drum-shaped ball as an example, the height of the drum-shaped ball has an impact to the result, in the case of ensuring reliability with the self-aligning technology, the higher the better, and the diameter of the pad should be as close as possible to the diameter of the connection between the drum-shaped ball and the pad, so as to reduce loss and improve transmission performance.