stacking micro via over buried via

Question

Anyone please help me on this. I have given micro via buried via stacking on my board. 
 whether micro via stacking over buried via will cause any reliability issue? is it not recommended to do this this method ? 
 Regards Jithindev MK

RFinley · Accepted Answer

Coincident over mechanical drills will be a yield problem if you don't pay for filled/planarized/plated core vias. Extra processing steps to minimize risk of opens. 
 Talk to your fabricator. Even If you have just one as coincident, you really need to pay for planarization.

masamasa · Answer

stacked vias may cause reliability issues such as cracks. so determining the diameter of vias and catch pads is a key to pass the reliability tests.

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stacking micro via over buried via

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