Comment by wbraun

Where are your weight figures coming from, they are not in the linked article.

Packaged semiconductors are going to be more metal interconnect / plastic encapsulation / ceramic insulation than silicon by weight.

These systems will also have a significant weight fraction in magnetic materials, either ferrite ceramics or amorphous metals.

Still a huge weight savings, but the weight fractions you are giving see off and are missing some important materials.