Solder ball size is definitely a factor in modern packaging cost! Silicon area is really expensive. That's why places like where I work are developing fan-out w

Solder ball size is definitely a factor in modern packaging cost! Silicon area is really expensive. That's why places like where I work are developing fan-out wafer level CSP. It has all the benefits of water level processing cost, but extra area for solder balls is made of cheap mold, not expensive silicon. These WLCSP parts are definitely not solderable at home though. But, with the rise of low cost PCB and assembly services, I'm not sure that matters as much as it used to. For example, one project I'm working on with a 384 ball BGA cost me twenty dollars to have placed and reflowed locally. And, new projects involve way fewer chips because of the scale of integration. As an analog engineer, it makes me sad, but I appreciate what I can make at home now!