The BM20 series from Hirose Electric is a 0.4 mm contact pitch board-to-board / board-to-FPC connector with a stack height of 0.8 mm. There is no restriction on pattern design, as the thin molding technology maintains the effective mating length of 0.2 mm while achieving complete insulation between the bottom side of the connector and the board.

The BM20 series has a mating self-alignment of 0.3 mm which is secured by the guide ribs. It has a shock-absorbing configuration with a dimple on the contact for connector robustness. This series is RoHS-compliant and Halogen-free and is available in positions 10, 20, 24, 34, and 40.