I don't know what handy panels are, but Baltic Birch / Finnish Birch / Russian Birch are most assuredly void free.If you're in the US and went to someplace like Home Depot or Lowe's you bought birch veneer plywood, but that is far from the product know as Finnish or Baltic Birch. I saw some birch veneer plywood in Lowe's recently that was actually lumber-core (what lumber is anybody's guess).
I believe 18 mm (3/4" stock) has 13 plys (1.4 mm each).