Lately I am really interested in Mediatek CPUs (ARM based) because they are available for very cheap at well known chinese shops.
But they are lacking in documentation. What I could find out though is that a almost 15 year old chip (MT6217) is only available in 0.65mm pitch BGA package?
So 0.65mm BGA was common in entry-level ARM CPUs (56 MHz) back then but today 0.65mm didn't become a cheap option at the common chinese PCB fabs - why is that? How did the PCB manufacturing process develop in the last 15 years?