B2501 Series | The Floating Board-to-Board Connector for Inverters, DC-DC, BMS & EPS

As one of the early players in the automotive electronics industry, BJD is committed to providing reliable solutions. Our connector solutions serve automotive electronics, industrial control, LED commercial displays, medical, security, and many other fields. BJD is a provincial "Specialized, Refined, Distinctive and Innovative" enterprise and a National High-Tech Enterprise with a CNAS-accredited laboratory, ensuring product quality!

01 Development Background

As the electrification of new energy vehicles continues to advance, powertrain modules such as inverters, DC-DC converters, BMS, and EPS keep reaching higher levels of integration and power density, and the vibration intensity of their operating environment has increased significantly as a result.

Traditional (non-floating, top-entry) female headers have two limitations in such scenarios: first, they impose tight tolerance requirements when multiple connectors are assembled at the same time, and accumulated tolerances can easily lead to poor assembly or insufficient contact; second, their vibration resistance is only moderate, and fretting corrosion tends to occur under long-term vibration, affecting the reliability of signal and power transmission.

In response to this market pain point, the industry is seeing growing demand for board-to-board connectors that combine floating mating capability with automotive-grade vibration resistance. The B2501 Series was developed precisely for this need: a dual C-shaped clamp contact structure improves contact reliability and vibration resistance, while the Bottom-entry design saves mounting space and flexibly accommodates a variety of stack heights — replacing traditional header solutions and meeting the dual requirements of connector reliability and space utilization in automotive powertrain systems.

02 Product Overview

The B2501 SERIES floating board-to-board connector features a unique dual C-shaped clamp contact structure that delivers excellent contact reliability and vibration resistance, meeting the stringent high-vibration requirements of automotive powertrain systems. Its unique back-side insertion technology inserts the terminals into the floating side from the back of the PCB, effectively saving mounting space while flexibly supporting a range of stack heights, including custom stack heights within a certain range.

Product Attributes

Materials

03 Product Features

• Compensates assembly tolerances for higher reliability
  The X/Y/Z three-axis float (e.g., ±0.5 mm / ±0.5 mm / ±0.4 mm on B2501) absorbs misalignment caused by multi-board stacking and accumulated structural tolerances, preventing stress concentration on contacts and solder joints.
• Significantly stronger vibration resistance
  The four-contact redundant design combined with floating compensation maintains stable contact even under continuous vibration, greatly reducing the risk of fretting corrosion, solder defects, and open circuits — exactly why it passes automotive-grade vibration testing.
• Higher assembly tolerance, ideal for automated lines
  The pre-guide chamfer structure supports blind-mating self-alignment and is relatively forgiving of placement accuracy and structural tolerances, making it suitable for high-volume automated assembly and reducing defect rates.
• Supports multiple stack heights
  Simply changing the pin header length flexibly accommodates different stack heights within the 4–10 mm range, so one connector covers multiple structural designs and reduces custom development costs.

04 Mating Scenarios

• Parallel mating — stack height H = 4–10 mm; the floating side is parallel to the SMT surface, and the mating side is inserted from the back of the PCB (SMT-type terminals are also available).
• Vertical mating — the floating side is mounted perpendicular to the PCB; the mating side is likewise inserted from the back of the PCB, and SMT-type terminals are also available.

05 Dimensions & Part Number Reference

Below are the outline dimensions of the B2501 floating side (receptacle) and the detailed dimension table for each pin count. Unit: mm; tolerance ±0.05; pitch tolerance is non-cumulative:

06 Applications

The B2501 SERIES floating board-to-board connector features a unique dual C-shaped clamp contact structure that delivers excellent contact reliability and vibration resistance, meeting the stringent high-vibration requirements of automotive powertrain systems. Its unique back-side insertion technology inserts the terminals into the floating side from the back of the PCB, effectively saving mounting space while flexibly supporting a range of stack heights, including custom stack heights within a certain range.

07 Product Summary

The B2501 SERIES floating pin-header/socket connector trades "cost, size, and high-speed performance" for "vibration reliability and assembly tolerance", and is purpose-built for applications such as NEV three-electric systems, where vibration is severe and assembly tolerances are large, but frequent mating cycles and ultra-high density are not required.

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