Hi Jack,
Even so they do not show directly, you have 8 internal layers plus 2 outer 
layers.
The most striking thing about this PCB is the thickness imbalance between the 
core layers [much thinner] and the prepreg layers [more than double the 
thickness of the core dielectric]. A good design should have these thicknesses 
balanced.
Also, having the prepreg layers so disproportionally thick can impact 
survivability of leadless soldering rocesses and long-term reliability [in severe 
operating environments], because the CTE(z) of the prepreg layers is quite a bit 
larger than the CTE(z) of the core layers, particularly above Tg.



Werner



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