Designed by Oregon State University ,Made by Storm Circuit in China.

This board is RF application ,the minimum trace is 3mil and the space is 3 mil too. But the most unusal is there are two cavities on board,the cavities are plated,it is not through from top to bottom .the depth is 10mil from top and plated .
The cavity is for bonding chips,the best surface finishing is ENEPIG for bonding.
Storm Circuit made lots of such RF application boards with high frequency material.
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Cavity design drawing

Real board ,3/3mil trace/space