Hirose Electric Co., Ltd. has developed the BM54 Series of board-to-board floating connectors. Mainly, they highlight a width dimension of 3.8mm, which is the smallest^*1 class for board-to-board connectors with a wide floating amount of ±0.4mm.

^*1 In board-to-board connectors with ±0.4mm floating range

Connection Reliability, Assembly Efficiency Inside Automotive Devices

In-vehicle cameras and LiDAR units are increasing due to the mandatory installation of rear cameras and the evolution of autonomous driving. Using non-floating connectors to internally connect these devices sometimes causes failure in the placement of multiple connectors on a single board. The inability to absorb the misalignment between boards causes this. Also, high-precision work such as optical axis adjustment is difficult when assembling cameras and high-performance LiDAR. In addition, sensing devices placed on the periphery of automobiles affect the vehicle design. Thus, miniaturization is also a key issue. To address these, there is a need for compact board-to-board connectors with a floating function to absorb misalignment between boards.

Automotive Quality Connector with ±0.4mm Floating Amount

In response, Hirose has developed the BM54 Series, which absorbs board misalignment with a large floating amount of ±0.4mm in the XY direction. Therefore, it improves contact reliability and contributes to more efficient application assembly. The width of this series is 3.8mm, which is the smallest-class board-to-board connector with a floating function. Accordingly, it contributes to the miniaturization of device applications. The two-point contact design and large effective mating length of ±0.4mm^*2 provide high contact reliability. Its heat resistance feature of up to 125°C makes it suitable for use in automotive environments.

^*2 In case of 3.5, 4.0 and 4.5mm

Features of BM54 Series

Hirose’s BM54 Series small floating board-to-board connector features 125℃ heat resistance and suits automotive specifications. It highlights 0.4mm pitch and 3.8mm width, considered the smallest class in floating board-to-board connectors. In terms of absorption of misalignment, it exhibits a floating range of ±0.4mm in the X and Y directions. Meanwhile, it has an effective mating length of ±0.3mm (stacking height = 3.0mm) and ±0.4mm (Stacking height = 3.5 to 4.5mm) in the Z direction. Also, it features high contact reliability with two-point contact. Additionally, it supports PCI-ex Gen4 (16Gbps) and MIPI D-PHY Ver.2.1 interfaces.

Future Product Development

The company targets to expand the newly developed BM54 Series with the following stacking heights and pin count variations in the future. Products under mass production are those with stacking heights of 3.0mm (No. of pos.: 30). Meanwhile, products under development planning will have stacking heights of 3.0, 3.5, 4.0, and 4.5mm (No. of pos. : 10, 20, 30, 40).

Hirose aims to further expand the market of these connectors as ultra-compact floating connectors that connect rigid circuit boards for in-vehicle equipment as well as consumer and industrial equipment.