If you have PTHs

Primarily, issues may occur in the PTHs. As you know, there are great CTE
diff within them, with Cu=17, solder=25, epoxy  x/y = 15 and epoxy z =
110-225 ppm/C.

- copper cracks in the barrel's upper region ( copper corner cracks)
- solder cracks in the same region (solder corner cracks)
- barrel deformation cracks



Micro vias

- plating cracks, i.e. cracks along the copper barrel
- barrel-to-trace cracks, i.e. interrupts between the barrel and the
horizontal copper trace
- delamination of the glass epoxy in the uppermost region around the vias


These are the general issues which may happen. There should be lots of
postings in TNs archive. And tons of reports on the web.


Inge





On 9 February 2011 18:12, Victor Hernandez <[log in to unmask]>wrote:

> Folks,
>
>   Given:
> -        FR4
> -       Th.  0.094 inch
> -       Layer Count   20
> -       Technology
> o       4 tier totem pole stack micro vias
> o       Buried conductive filled blind vias
> -        Post 3x and 6x solder float test
> -        Cross section
>
> What are some of the expected anomaly to look for?
>
> Victor,
>
>
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