The final tier requires absolutely ABSURD quantities of science packs. Why in the world?!? No structure in the game needs more than a few thousand packs just to research how to make them. Even the Space Age tier 4 belts only need 500 Metallurgic packs.

It's bad enough that you need to go all the way to Promethium and gather up science packs from every planet in the game in addition to that. But one hundred thousand of each one of those?!? You gotta be out of your mind! xD Usually the roadblock is actually getting to the point where you can DO the science, not spending an eternity farming them before you can even know how to make the belts.

A more vanilla-friendly tech progression might be:
tier 1: 20 packs
tier 2: 200 packs
tier 3: 300 packs
tier 4: 500 packs
tier 5: 1000 packs (not 4000)
tier 6: 2000 packs (not 10,000 D:)
tier 7: 4000 packs (not 100,000 o_O)

As one other note, I noticed that your tier 5 belts don't actually require the tier 4 research to be completed. So you could technically research the tier 5 without even researching the tier 4 at all, which feels a bit awkward. The internal name of this technology is "turbo-transport-belt" for your prerequisites section.