What is "thermal via" in substrate of package

[R1kky]

unfortunately didn't find exact explanation of what is "thermal via" what is the main difference to simple via.

please explain. sorry for dummy question.

 

[dick_freebird]

In a ceramic package, thermal vias are punched / drilled &
refilled with metal to improve thermal conductivity. They
may, or may not, be used for an electrical path as well.
It is an alternative to a heat-slug design which can be
more of a stretch to design / qualify. Thermal vias can
be a couple-of-layers mod to an existing package layup.
These vias pass through the body, while normal vias are
captive (across inner layers, but not exposed outside).
Internal vias have no impact to hermeticity and so on,
tend to be smaller and use the internal tungsten metal
rather than something like CuW (better for thermals).

 

[R1kky]

Re: What is "thermal via" in substrate of package

thanks a lot for overview, does it work for as well for plastic packages as well?

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thanks a lot for overview, does it work for as well for plastic packages as well?

for my understanding (please correct me if i'm wrong):
typical vias - inside substrate, didn't placed in top and bottom layers. usually filled with tungsten material.
thermal vias - connect top and bottom layers (balls with pads), its inner layers could be used in electrical path. Thermal vias filled with "thermal good" materials (CuW for example).