Experts,

I ran into misunderstanding often on via classification on PCBs  and like to have clear understanding on this forum.
As layout designer I classify vias
        - based on drill depth as Blind via(external to internal), Buried via(with in internal) and through hole via (external to external).
        - based on via stack as Stacked via(Blind/Buried vias placed at same locations) and staggered via (blind/buried via placed apart may have pad overlaps)

I am fine and clear up to hear.

Now, as I discuss with latest technologies /package
        - on tighter pitch BGAs say 0.4mm pitch BGA's the VIP(via in pad) come into role and need via filling.
        - high power ICs with thermal pad which needs thermal vias for heat dissipation, these via need plugging

Here the discussion starts with Fabricator's and lead to misunderstanding on via definitions
- They call  Microvia to plate and shut copper
        What micro via means?
                a) Some refers to  Blind via but with limitation in the depth that the can only go one layer down from external layers with drill size less than 6mils.
                b) some inform they are Via in Pad using blind vias which is of drill size 6mils and less
                c) some refers to any via of drill size less than 6mils and is laser drilled called Microvia and the via doesn't matter blind/buried/through hole
                d) few other says its HDI(- High density interconnect) via and this includes Blind and buried but not through hole via

I am totally lost here - Please help to understand the via terminologies in Fabrication world specifically Microvia.

Thanks in advance for your inputs.

Thanks,
Nagaraj.


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